EXCHANGE 


KENTUCKY 
GEOLOGICAL  SURVEY 

J.  B.  HOEING,  STATE  GEOLOGIST 


IN  CO-OPERATION  WITH 


UNITED  STATES 
GEOLOGICAL  SURVEY 

GEORGE  OTIS  SMITH,  DIRECTOR 


REPORT  ON  THE  PHOSPHATE  ROCKS 
OF  CENTRAL  KENTUCKY 


FRANKFORT,  KY. 
1915 


v; 


THE  STATE  JOURNAL  COMPANY 

Printer     to  the  Commonwealth 

Frankfort,    Ky. 


THE  CENTRAL  KENTUCKY  PHOSPHATE  FIELD 


By 


W.  C.  Phalen. 


TABLE  OF  CONTENTS 


Page 

Introduction 1 

F'ield  work 2 

Geography  and  topography  2 

Geology 4 

Stratigraphy  4 

Description  of  formations  6 

"Wilmore"  and  Bigby  (?)  limestones 6 

Flanagan  limestone  7 

Brannon  cherty  member  7 

Woodburn  phosphatic  member  9 

Rocks  overlying  the  Flanagan  limestone 11 

Structure  11 

Discovery  of  the  field  12 

The  phosphate  rock 15 

Type  of  rock 15 

Mode  of  occurrence  16 

Distribution  and  character  of  the  phosphate  beds 21 

Sections  and  analyses  of  phosphate  rock  23 

Wallace  district 23 

District  west  of  Midway 29 

Frankfort  and  Forks  of  Elkhorn  district  . 31 

Lexington  district  32 

Localities  to  be  prospected  36 

Method  of  prospecting 40 

Method  of  collecting  samples 43 

The  local  quarry  industry  as  a  guide  to  prospecting 43 

The  composition  of  the  phosphate  rock 44. 

Origin  ; 46 

Source  of  the  phosphate  46 

Original  mode  of  occurrence  46 

The  method  of  concentration 48 

The  brown  phosphate  rock  industry  52 

General  conditions 52 

Grades  of  commercial  brown  phosphate  rock  54 

Preparation  of  phosphate  rock  for  market 55 

Removal  of  overburden  56 

Costs  of  removal  of  overburden  57 

Methods  of  mining  58 

Working  cutters 59 

The  cost  of  mining  phosphate  rock 60 


Page 

Washing  and  drying 61 

Conservation  of  fines 62 

The   phosphate  industry  at  Wallace,   Kentucky 03 

Transportation   facilities 61 

Raw  rock  phosphate 65 

Phosphatic  limestone  as  a  source  of  phosphate  66 

The  future  of  low  and  intermediate  grade  phosphate  rock 67 

General    remarks 67 

Chemistry  of  process 68 

Experimental  work  in  the  west  69 

Chemical  methods 69 

Electrical    methods 71 

The  future  outlook  for  Kentucky 74 

Bibliography 77 


Mohawkian  Rocks. 


Phosphatic  area 
near  Midway. 


Rocks  above  Mohawkian 


Geologic   Map   of  Central   Kentucky,   showing  the   distribution   of 

Mohawkian    (Middle   Ordovician)    Rocks. 

Scale:   1  inch=10  miles. 


THE  CENTRAL  KENTUCKY  PHOSPHATE  FIELD 

By  W.  C.  PHALEN. 


INTRODUCTION. 


Tho  object  of  .this  report  is  mainly  to  present  to  the 
public,  unfamiliar  with  Kentucky's  resources,  data  and 
information  of  general  interest  bearing  on  the  phosphate 
deposits  of  the  State.  In  it  are  described  the  location  and 
geographic  distribution,  the  extent,  and  relative  im- 
portance of  the  deposits  under  present  conditions  of  the 
phosphate  and  fertilizer  industry,  and  what  may  be  ex- 
pected of  them  as  time  'goes  on  and  new  processes  for 
working  them  are  developed.  The  methods  of  mining 
and  preparing  brown  rock  phosphate  for  market  as 
practiced  in  the  neighboring  state  of  Tennessee  are  also 
briefly  outlined,  for  without  doubt  Tennessee  practice 
and  experience  will  be  utilized  when  the  Kentucky  de- 
posits come  to  be  more  generally  worked. 

The  element  phosphorus  is  one  of  the  three  es- 
sentials of  the  commercial  fertilizers  of  the  present  day. 
It  is  supplied  to  plants  in  the  form  of  acid  phosphate, 
raw  ground  rock  phosphate,  basic  slag,  and  various  bone 
products,  such  as  steamed  bone  meal,  raw  bone  meal, 
bone  ash,  and  bone  black.  Of  these  various  substances 
acid  phosphate  is  the  most  largely  used.  It  forms  one 
of  the  principal  ingredients  of  nearly  all  commercial 
fertilizers.  It  is  prepared  from  the  naturally  occurring 
phosphate  rock  and  the  essential  ingredient  in  this  rock 
is  calcium  phosphate  which  is  also  often  referred  to  as 
bone  phosphate  of  lime  or  bone  phosphate,  or  simply 
abbreviated  to  "BPL".  Any  or  all  of  these  terms,  which 
mean  the  same  thing,  will  be  used  in  this  report. 

Any  extensive  deposit  of  phosphate  rock  in  the 
I 'nited- States  is  either  of  present  or  prospective  import- 
ance. Those  in  central  Kentucky,  though  not  yet  worked 
to  any  marked  extent,  occupy  a  wide  territory,  are  of 
intermediate  grade,  and  therefore  constitute  a  reserve 


supply  of  inportance.  They  were  investigated  by  the 
writer  in  191.4  and  1915  and  the  following  descriptions 
summarize  the  results  obtained. 

This  report  is  primarily  an  economic  report  and  the 
geologic  features  are  only  considered  in  the  light  that 
they  throw  on  the  economic  problems  involved. 

FIELD  WORK. 

The  field  Avork  on  which  this  report  is  based  was 
done  in  September  and  October,  19.14,  and  in  June,  1915. 
It  extended  over  the  better  known  phosphate  area  lying 
between  the  towns  of  Versailles  and  Midway,  Wood- 
ford  County,  especially  in  the  vicinity  of  Wallace.  Con- 
siderable work  was  also  done  west  and  northwest  of 
Midway,  between  the  Louisville  and  Nashville  Eailroad 
and  South  Klkhorn  (/reek.  Studies  were  also  made  in 
the  vicinity  of  the  Forks  of  Elkhorn  Creek,  Franklin 
County,  in  and  around  Lexington,  Fayette  County,  and 
in  a  few  isolated  localities  which  will  be  mentioned  in 
the  subsequent  descriptions. 

The  writer  gladly  acknowledges  the  efficient  help 
rendered  him  by  Mr.  P.  B.  Winn,  of  Lexington  and  Win- 
chester, Kentucky,  in  the  field  work,  and  also  the  many 
valuable  suggestions  made  by  Professor  A.  M.  Miller, 
of  the  State  University  at  Lexington.  References  to  the 
work  of  Miller  will  be  made  at  the  appropriate  places 
in  the  text. 

During  the  course  of  this  work  nearly  two  hundred 
shallow  drillings  weie  made,  the  cores  carefully  sampled, 
and  analyses  of  the  samples  together  with  others  were 
made  in  the  laboratories  of  the  United  States  Geological 
Survey  by  W.  0.  Wheeler  and  E.  M.  Kanini. 

GEOGRAPHY  AND  TOPOGRAPHY. 

The  greater  part  of  the  territory  discussed  in  con- 
nection with  the  Kentucky  phosphate  field  occurs  in  the 
Georgetown  quadrangle.  This  quadrangle  comprises  a 
large  part  of  Fayette,  Woodford  and  Scott,  and  small 
parts  of  Franklin  and  Jessamine  counties.  Studies  were 
also  made  in  parts  of  Franklin  County  off  the  northwest 
corner  of  the  Georgetown  quadrangle  and  in  the  vicinity 
of  Pine  Grove  Station,  Clark  County.  The  phosphate 
areas  within  the  Georgetown  quadrangle  in  Franklin 


County  have  been  studied  by  A.  M.  Miller*  and  descrip- 
tions of  the  phosphate  areas  themselves  have  been  pre- 
pared by  A.  E.  Foerste.f  The  writer  acknowledges  the 
help  received  from  the  reports  of  these  geologists  and 
due  credit  is  given  to  them  in  the  proper  places  in  these 
descriptions. 

The  low  broad  hills  and  the  rolling  topography  are 
characteristic  of  this  beautiful  country,  which  is  of  the 
type  known  to  geologists  as  a  peneplain.  The  important 
phosphate  deposits  occur  at  the  surface  of  this  old  pene- 
plained  aica,  that  is,  an  area  which  has  long  been  ex- 
posed to  erosion  and  which  has  been  worn  down  to  an 
approximately  level  surface  with  most  of  the  broad  level 
hill  tops  now  between  900  and  1,000  feet  above  sea. 

The  rocks  in  this  section  containing  the  phosphate 
are  entirely  limestones.  The  exposure  to  weathering  of 
a  soluble  rock,  such  as  limestone  is  under  ordinary  con- 
ditions, has  here  brought  about  fundamental  changes  in 
which  have  been  involved  the  removal  of  a  large  part  of 
the  country  rock.  The  removal  of  this  rock  has  been  ac- 
complished both  by  chemical  and  mechanical  means. 
Limestone  as  it  usually  occurs  is  mixed  with  more  or  less 
of  insoluble  hydrous  silicates  of  aluminum  (clay).  The 
limestones  in  this  region  contain  also  the  insoluble  phos- 
phate rock.  The -limestone  has  been  removed,  probably 
largely  in  the  form  of  the  soluble  bicarbonate  Ca  H., 
(CO*) 2  and  the  clay  left  after  the  solution  of  the  Ca  CO3 
hos  been  carried  off,  in  part  at  least,  mechanically.  There 
is  scarcely  any  doubt  that  some  phosphate  rock  has  been 
carried  off  in  this  manner  and  thus  wasted  for  all  time. 

In  recent  times  the  rate  of  removal  of  the  residual 
material,  clav  and  phosphate  rock,  has  been  slower  than 
its  accumulation,  and  in  some  places  as  revealed  in  na- 
tural exposures  and  drillings,  it  is  10  or  more  feet  thick. 
In  many  other  places,  of  course,  the  basal  limestone  out- 
crops. 

The  principal  streams  within  the  areas  under  dis- 
cussion are  North  and  South  Elkhorn  Creeks  and  their 
tributary  branches.  Fortunately  South  Elkhorn  Creek  is 
not  too  remote  to  be  considered  as  a  possible  source  of 

*MiJlpr.  Arthur  M.,  Geology  of  the  Georgetown  quadrangle;  Kentucky 
Geological  Survey.  Series  4,  Vol.  1,  Pt.  1,  1913.  po.  S17-364.  Geology  of 
Franklin  County;  Ky.  Geol.  Survey,  Series  4,  Vol.  2,  Pt.  3,  1914,  pp.  11-87. 

fFoerste,  A.  E.  The  phosphate  deposits  in  the  upper  Trenton  lime- 
stones of  Central  Kentucky;  Ky.  Geol.  Survey,  Series  4,  Vol.  1,  Pt.  1, 
1913,  pp.  SfH-Ui. 


wash  water,  great  quantities  of  which  are  needed  in 
phosphate  mills  for  washing  purposes.  In  a  limestone 
region  where  sinks  abound  and  where  much  of  the  drain- 
age is  below  ground,  the  presence  of  a  stream  like  South 
Elkliorn  Creek  may  prove  to  be  of  the  greatest  economic 
importance  to  an  industry  requiring  a  very  cheap  and 
abundant  water  supply.  The  topographic  and  geologic 
map  shows  the  great  paucity  of  important  streams  ex- 
cept South  Elkliorn  Creek  in  the  neighborhood  of  the 
phosphate  deposits. 

The  meandering  character  of  the  Elkliorn  Creeks  is 
pronounced.  The  presence  of  streams  would  be  hardly 
suspected  when  the  country  is  viewed  from  a  hilltop. 
Only  the  dense  growth  along  them  indicates  their  courses. 
There  seems  little  doubt  that  the  irregular  stream  courses 
have  been  inherited  or  retained  from  a  period  in  their 
history  when  they  flowed  over  a  low  broad  plain.  As  the 
region  has  been  elevated  they  have  cut  down  or  deepened 
their  channels,  but  this  has  taken  place  with  few  excep- 
tions along  their  original  courses.  Such  streams  are 
said  to  have  intrenched  themselves,  and  their  meanders 
are  known  as  intrenched  meanders. 

GEOLOGY. 
STRATIGRAPHY. 

The  following  notes  on  general  stratigraphy  and 
structure  of  the  quadrangle  are  compiled  largely  from  the 
reports  of  Prof.  A.  M.  Miller,  as  the  writer  spent  less 
than  three  months  in  the  area,  working  chiefly  on  the 
economic  problems  of  the  phosphate  beds  alone. 

The  country  rocks  associated  with  the  phosphate 
rock  deposits  are  all  limestones  of  different  lithology 
and  degrees  of  purity.  The  chief  foreign  ingredients  in 
them  are  clay,  chert,  and  the  phosphate  rock  itself.  They 
are  all  of  marine  origin  and  belong  to  the  middle  part 
of  the  Ordovician  system;  their  total  thickness  is  ap- 
proximately 330  feet. 

The  best  stratigraphic  section  in  the  vicinity  of  the 
area  which  the  writer  knows  of  is  on  the  hill  road  at  the 
Old  Crow  Distillery  near  the  mouth  of  Glenn's  Creek.  The 
locality  is  about  5  or  6  miles  wrest  of  the  w^est  boundary 
of  the  quadrangle.  The  following  illustration  (Figure  1) 


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Cyclonema  varicosum 
Hebertella  sinuata 


Constellaria  teres 
Stromatocerium 

Columnaria  halli 
Rhynchotrema  inaequivalve 


Stromatocerium  reef 
Rhynchotrema  inaequivalve 


Prasopora  simulatrix 


Dalmanella  bassleri  layers 


Fig.  1. 

Geological  section  exposed  at  the  Old  Crow  Distillery  from  level 
of  Glenn's  Creek  to  top  of  hill  on  North  Side  of  the  creek,  taken  along- 
steep  road  intersecting  the  pike  at  the  distillery.  (After  A.  M.  Miller.) 
Ky.  Geol.  Survey,  Series  IV,  Vol.  1,  Part  1,  1913. 


represents  the  section  at  this  locality  as  given  by  Pro- 
fessor Miller. 

The  phosphate  deposits  of  the  Georgetown  quadran- 
gle occur  chiefly  in  the  beds  to  which  the  name  Woodburn 
is  applied  in  the  section  quoted  in  Fig.  1.  These  beds, 
together  with  the  underlying  Brannon  bed  of  Miller, 
correspond  to  the  Flanagan  chert  of  M.  R.  Campbell  in 
the  Richmond  folio  of  the  United  States  Geological  Sur- 
vey. 

DESCRIPTION  OF  FORMATIONS. 
"  WILMORE"  AND  BIGBV  (  ?)  LIMESTONES. 

The  rocks  of  this  area  to  which  the  names  Wilmore 
and  Bigby  have  been  applied  by  Professor  Miller  con- 
sist of  thin-bedded  limestones  with  some  shale  between  the 
layers.  There  is  no  distinct  lithologic  or  stratigraphic 
break  between  them.  The  name  "Wilmore  is  preoccupied 
by  the  Wilmore  sandstone  member  of  the  Conemaugh 
formation,  and  it  is  therefore  quoted  in  this  report.  The 
rocks  called  Bigby  by  Professor  Miller  are  correlated 
by  him  with  the  Bigby  limestone  of  southwestern  Tennes- 
see. As  this  correlation  is  not  established  the  name  Big- 
by ( ?)  limestone  is  used  in  this  report.  The  total  thick- 
ness of  these  formations  within  the  Georgetown  quad- 
rangle is  about  90  feet.  Of  this  total  thickness  65  to  75 
feet  belong  to  the  Bigby  (?)  limestone  and  the  rest, 
namely  15  to  25  feet,  belong  to  the  "Wilmore."  Accord- 
ing to  Miller  the  "Wilmore"  is  characterized  by  the 
brachiopod  Dalmanella  bassleri  and  the  "chocolate 
drop"  or  hemispherically  shaped  bryozoan  Prasopora 
simulatrix. 

The  Bigby  (?)  formation  contains  more  abundantly 
them  any  other  formation  the  brachiopod  Rhynchotrema 
inaequivalve.  Hebertella  frank  fort  en  sis,  another  brach- 
iopod, is  also  abundant  in  the  Bigby  (?)  and  upper  part 
of  the  "Wilmore,"  reaching  its  culmination  lower  down 
in  the  section  than  RhyncHotrema  inaequivalve.  At  the 
top  of  the  Bigby  (I),  and  confined  to  a  vertical  range 
of  not  over  10  feet,  is  a  very  characteristic  assemblage 
of  fossils  comprising  two  bracMopods,  Dmprthis  ulrichi 
and  Strophomena  vicina,  a  bryozoan  of  globular  habit, 
Cyphotrypa  frankfortensis,  and  a  large  coralline  fossil 


Stromato cerium  pustulosuni,  together  with  other  bryo- 
zoa. 

"The  coralline  fossil  Stromato  cerium  putulosum  is 
usually  so  abundant  at  this  horizon  as  to  indicate  that  it 
formed  .a  reef  in  this  region  in  the  ancient  Ordovician 
sea."  It  is  especially  abundant  in  the  northern  part  of 
the  Georgetown  quadrangle  and  as  far  south  as  the  lati- 
tude of  Midway.  In  places  it  is  as  much  as  6  feet  in 
thickness  and  as  its  top  is  practically  at  the  base  of  the 
next  overlying  formation  (the  Flanagan),  it  has  an 
economic,  as  well  as  stratigraphic  significance,  for  the 
reason  that  all  important  phosphate  deposits  are  likely 
to  be  found  either  close  above  or  close  below  it.  Accord- 
ing to  Foerste  phosphate  rock  also  occurs  locally  in  the 
upper  part  of  the  Bigby  (  .')  limestone. 

FLANAGAN  LIMESTONE. 

The  term  Flanagan  chert  was  given  by  M.  R.  Camp- 
bell in  the  Richmond  Folio  of  the  United  States  Geo- 
logical Survey  to  the  next  overlying  formation.  The 
term  was  applied  to  the  rocks  occupying  the  interval 
between  the  Lexington  and  Winchester  limestones,  the 
latter  terms  being  practically  the  same  as  Linney's 
Trenton  and  Hudson  formations  as  used  in  the  latter  ?s 
reports  on  the  counties  in  the  blue  grass  region  for  the 
Shaler  and  Procter  Kentucky  State  Surveys. 

According  to  Miller*  only  the  lower  13  to  15  feet 
of  the  Flanagan  consists  of  siliceous  limestone  which 
forms  chert  on  weathering.  The  cherty  character  is  not 
at  all  conspicuous  excepting  as  the  result  of  ordinary 
atmospheric  weathering  processes  where  the  beds  are 
at  the  surface.  The  remainder  of  the  Flanagan  con- 
sists of  30  to  40  feet  of  thin-bedded,  granular,  phosphatic 
limestone.  The  lower  cherty  beds  are  herein  called 
Brannon  cherty  member,  and  the  upper  or  phosphatic 
beds  are  called  Woodburn  phosphatic  member. 

BRANNON  CHERTY  MEMBER. — The  beds  to  which 
Miller  has  applied  the  name  Brannon  in  his  description 
of  the  rocks  of  the  Georgetown  quadrangle  consist  of  13 
to  1.5  feet  of  siliceous  limestone  which  forms  chert  on 
weathering.  The  beds  are  named  for  exposures  at 

*Miller,   A.   M.,    Geology  of  the  Georgetown  quadrangle;  Ky.   Geol.   Sur- 
vey,   Series  IV.,   Vol.   1,    Pt.   1,    1913,    p.   324. 


Brannon  Station,  on  the  Queen  and  Crescent  Railroad, 
a  short  distance  south  of  the  southern  boundary  of  the 
Georgetown  quadrangle.  These  rocks  are  regarded  by 
Miller,  Foerste  and  Ulricli,  as  representing  the  lower 
or  cherty  part  of  Campbell's  Flanagan  chert. 

It  is  the  upper  part  of  the  Brannon,  with  its  highly 
contorted  or  bouldery  layers  (see  PI.  1  and  "2)  that  is  so 
characteristic  and  it  is  this  portion  which  furnishes 
most  of  the  chert  at  its  weathered  outcrop.  AVhen  freshly 
exposed  the  Brannon  is  very  firm  and  hard  and  requires 
blasting  to  remove  it.  It  is  a  good  water  bearer  and  con- 
sequently its  outcrop  is  generally  marked  by  the  pres- 
ence of  springs.  The  Big  Spring  at  Versailles  is  at  this 
horizon  and  also  what  are  known  as  the  Maxwell  or  Sink- 
ing Springs  at  Lexington.  The  Big  Spring  at  Spring 
Station  is  also  near  this  horizon.  It  is  pre-eminently  the 
formation  occurring  in  the  numerous  sinks  found  in  this 
quadrangle.  This  latter  association  may  be  due  to  its 
tendency  to  resist  temporarily  destruction  by  solution 
and  to  form,  therefore,  the  root's  of  caverns.  Later,  when 
brought  to  the  surface  by  denudation,  it  goes  to  pieces 
rapidly,  is  decomposed  into  chert  and  the  roof  of  the 
cavern  falls  and  a  sink  results.  There  are  instances 
where  the  collapse  of  a  cavern  roof  has  taken  place 
suddenly  and  has  entrapped  grazing  stock. 

As  may  be  inferred  from  the  behavior  of  this  lime- 
stone under  conditions  of  weathering,  natural  exposures 
of  the  firmer  layers  are  rare.  The  best  exposures  are 
along  railroad  cuts  and  in  other  artificial  excavations 
and  in  sinks  of  rather  recent  development.  The  Brannon 
is  splendidly  exposed  in  a  cut  on  the  Cincinnati,  New 
Orleans  and  Texas  Pacific  Railroad  (Queen  and  Crescent 
route)  in  Lexington  near  the  Virginia  Avenue  (Lottie 
Street)  bridge.  It  is  usually  a  spring  horizon  and  the 
water  comes  out  directly  above  the  contorted  limestone 
layer  which  is  from  1  to  1%  feet  thick  at  this  locality. 
The  cherty  phosphatic  layer  shows  above  the  contorted 
layer,  but  very  little  of  it  is  in  massive  form.  (See 
plate  1.) 

Near  where  the  photograph  was  taken  the  phos- 
phatic layer  is  8  to  1.0  feet  thick,  but  owing  to  the  pres- 
ence of  considerable  wash  the  exact  thickness  is  not 
readily  ascertained. 


The  Brannon  resembles  a  sandy  limestone  at  this 
locality  and  thin  bands  of  blue  shale  up  to  2  feet  in  thick- 
ness were  observed.  It  is  very  irregularly  bedded — a 
condition  especially  noticeable  where  the  base  of  the 
upper  or  contorted  layer  rests  on  that  containing  the 
blue-drab  shale.  This  contact  is  so  irregular  that  non- 
conformity or  even  faulting  is  suggested.  In  addition 
to  this  locality,  eight  other  localities  where  the  Brannon 
outcrops  are  listed  by  Miller. 

The  Brannon  is  of  interest  because  in  most  instances 
it  forms  the  base  of  the  richest  phosphate  deposits  of 
this  region. 

WOODBURX  PHOSPHATIC  MEMBER. — The  strata  to 
which  the  name  Woodburn  has  been  applied  by  Miller 
are  described  by  him  as  consisting  of  "about  30  to  40  feet 
of  thin  bedded,  granular,  phosphatic  limestone.  The 
name  comes  from  the  celebrated  Alexander  estate,  in 
Woodford  County,  where  the  beds  are  said  to  be  very 
typically  developed,  especially  as  regards  their  most 
distinctive  feature,  the  possession  of  phosphate.  The 
most  conspicuous  fossil  in  this  formation  is  the  coral, 
Cohimnaria  lialli.  It  is  commonly  found  in  a  silicified 
condition  weathered  out  from  its  matrix  and  found  loose 
in  the  deep,  dark  red  soil  formed  from  the  decay  of  the 
limestone  at  its  horizon.  Another  very  common  fossil  in 
this  formation  is  the  very  small  gastropod  Cyclora 
minula.  This  fossil  occurs  only  as  phosphatic  casts  of 
the  inside  of  the  shell,  and  its  presence  in  association  with 
the  more  phosphatic  phases  of  the  rock  suggests  strongly 
that  the  animal  which  formerly  inhabited  the  shell  played 
an  important  part  in  the  original  segregation  of  the  phos- 
phate of  lime  from  the  sea  water. ' '  According  to  Miller, 
Foerste  and  Ulrich,  the  Woodburn  is  equivalent  to  the 
upper  and  major  part  of  the  Flanagan  chert  of  Camp- 
bell. 

At  the  old  workings  of  the  Central  Kentucky  Phos- 
phate Company  at  Wallace,  a  good  opportunity  is  pre- 
sented to  study  the  stratigraphic  position  of  the  phos- 
phate rock  deposits  themselves.  From  the  data  which 
Foerste*  obtained  he  concluded  that  "the  diggings  so 
far  made  by  the  Phosphate  Company,  at  their 

*Foerste,  A.  E.  The  phosphate  deposits  in  the  upper  Trenton  limestone 
of  Central  Kentucky;  Ky.  Geol.  Survey,  Series  IV.,  Vol.  I.,  Pt.  I.,  1913, 
PP.  412-413. 


plant  southeast  of  Wallace,  belong-  to  the  upper  part  of 
the  Benson  or  Bigby  bed,  and  not  to  the  Woodburn  bed. 
This  is  confirmed  by  the  latest  diggings  made  at  the 
plant.  Here  the  basal  part  of  the  Brannon  bed  was  ex- 
posed about  half  way  up  the  hill  slope,  above  the  level 
of  the  first  three  strips  of  phosphate  rock,  50  feet  wide, 
so  far  removed.  Here  Dinoilldx  ubiclil  and  Stromato- 
cerium  occurred  in  the  upper  part  of  the  phosphate  rock, 
beneath  the  base  of  the  Brannon  layer,  clearly  indicating 
the  geological  horizon.  The  phosphate  rock  struck 
northeast  of  the  house1  on  the  Steele  farm,  about  a  mile 
and  a  quarter  east  of  Wallace  Station,  however,  belongs 
to  the  upper  part  of  the  Woodburn  horizon. 

"It  is  evident  that,  locally,  weathering  away  of  the 
Woodburn  bed  has  resulted  in  the  concentration  of  phos- 
phatic  material  at  the  top  of  the  next  underlying  lime- 
stone, which  in  this  case  is  the  Benson  or  Bigby  bed.  It 
is  interesting  that,  at  the  only  locality  at  which  so  far 
any  actual  commercial  development  of  the  phosphate 
field  has  been  undertaken,  the  only  workable  rock  so 
far  exploited  should  belong  to  the  Benson  and  not  to  the 
Woodburn  horizon.  Aside  from  this  limited  area  in  the 
neighborhood  of  Wallace,  there  are  also  other  localities 
at  which  phosphate  rock  occurs  in  the  upper  part  of  the 
Benson  bed,  but  by  far  the  greater  part  of  occurrences 
of  phosphate  deposits,  taking  the  field  as  a  whole,  occur 
in  the  Woodburn  bed,  and  this  is  especially  true  when 
the  un weathered  rock  is  taken  into  account.  This  sug- 
gests the  origin  of  the  most  of  the  phosphatic  deposits 
in  central  Kentucky  in  the  Woodburn  horizons,  although 
locally  concentration  may  have  extended  downward  into 
the  upper  part  of  the  Bigby. 

"The  occurrence  of  StropJiomena  vicina  in  the  phos- 
phatic layers  in  the  upper  part  of  the  Stark  quarry,  a 
mile  and  a  half  south  of  Wallace,  suggests  that  these 
layers  also  belong  to  the  upper  part  of  the  Benson  sec- 
tion." 

The  phosphatic  rock  deposits  are  proved,  therefore, 
to  extend  through  a  considerable  stratigraphic  interval. 
It  is  clear  from  the  descriptions  that  the  phosphate  bear- 
ing beds  cannot  be  represented  on  the  map  by  a  single 
line,  and  not  very  readily  by  a  band  as  in  ordinary  geo- 
logic mapping. 

The  Woodburn  abounds  in  sinks.      ~    * 

10 


ROCKS  OVERLYING  THE  FLANAGAN  LIMESTONE. 

Only  the  lower  member  of  the  formation  overlying 
the  Flanagan  is  of  interest  or  importance  in  this  report 
for  the  reason  that  it  occurs  close  above  the  phosphate 
rock  horizon  and  thus  may  prove  of  great  assistance  in 
helping  to  locate  it.  This  member  is  a  gastropod  horizon. 
In  western  Woodford  and  adjacent  parts  of  Franklin 
County  the  shells  of  gastropods  are  massed  together  in 
a  ledge  of  cherty  limestone  about  5  or  6  feet  thick.  In 
its  massive  condition  this  limestone  is  found  in  the 
western  and  southwestern  parts  of  the  Georgetown  quad- 
rangle south  of  South  Elkhorn  Creek.  Its  former  pres- 
ence in  the  southwestern  quarter  of  the  area — that  is 
in  the  region  south  and  west  of  South  Elkhorn  Creek- 
may  be  readily  traced  by  means  of  its  outliers  and  the 
abundance  of  gastropod  chert  debris  found  in  the  soil. 
The  latter  on  account  of  its  resistant  character  may 
even  be  found  over  areas  from  which  the  formation  has 
long  been  removed  by  weathering,  if  it  ever  existed  in 
these  parts.  Where  it  occurs  as  a  distinct  horizon  the 
phosphate  rock  bed  should  be  looked  for  below  it  on  the 
hiils. 

STRUCTURE. 

The  area  of  the  phosphate  deposits  is  on  the  western 
flank  of  the  Cincinnati  geanticline — a  broad,  low  dome 
toward  the  center  of  which  the  rocks  outcropping  be- 
come lower  and  lower  in  the  geological  time  scale.  The 
rocks  in  this  region,  therefore,  dip  from  west  to  north- 
west at  very  low  angles — so  low  that  the  dips  cannot 
be  determined  instrumentally,  that  is  with  a  clinometer, 
but  must  be  reckoned  over  broad  areas  on  the  basis  of 
actual  elevations  on  particular  beds.  The  average  rate 
of  this  dip  is  about  ten  feet  per  mile  and  the  main  streams 
fall  at  approximately  the  same  rate  in  the  same  direction, 
thus  running  over  approximate  dip  slopes.  It  follows, 
therefore,  that  the  highest  lands  are  found  in  the  south- 
east part  of  the  region  and  the  lowest  in  the  northwest. 
The  relief  in  the  Georgetown  quadrangle  is  about  ;>50  feet, 
the  difference  between  1050  feet  along  the  Nicholasville 
pike  in  the  southeastern  part  of  the  Georgetown  quad- 
rangle, and  700  feet,  the  approximate  elevation  of  South 
Elkhorn  Creek  where  it  leaves  the  quadrangle. 

11 


The  uniformity  of  dip  to  the  northwest  has  been 
interfered  with  in  places  by  disturbances  which  have  re- 
sulted in  faults.  Most  of  these  are  of  slight  vertical 
throw  and  of  limited  extent  in  surface  outcrop.  They 
are  "tension  or  normal77  faults  and  have  a  wide  drag 
zone,  for  which  reason  the  stratigraphic  throw  is  great 
compared  with  the  vertical.  Most  of  those  located  occur 
in  pairs,  one  of  which  may  be  considered  the  primary 
and  the  other  the  secondary  or  compensating  fault.  An 
illustration  of  other  minor  movements  in  the  rocks  is 
shown  in  Plate  III.  The  faults  so  far  as  known  do  not 
involve  those  areas  where  the  important  phosphate  de- 
posits are  found. 

DISCOVERY  OF  THE  FIELD. 

There  seems  to  be  no  question  but  that  the  distinc- 
tion of  having  called  attention  to  phosphate  in  the  lime- 
stones of  central  Kentucky  belongs  to  Dr.  Eobert  Peter, 
Chemist  of  the  Kentucky  Geological  Survey,  under  the 
administration  of  N.  S.  Shaler.  This  wras  done  as  early 
as  April,  1849,  in  the  Albany  Cultivator  of  NewT  York.* 
It  was  Dr.  Peter  also  who  first  pointed  out  the  associa- 
tion of  phosphate  and  cyclora  and  the  dependence  of  the 
soils  of  the  blue  grass  region  for  their  fertility  on  the 
presence  of  phosphate  rock. 

In  the  report  by  Dr.  Peter  to  State  Geologist  Shaler, 
dated  February,  1877,  there  is  given  the  analysis  (No. 
1778)  of  a  phosphatic  limestone  from  McMeekin7s  quarry 
(see  Plate  IV.)  on  the  Newtown  pike,  3  miles  north  of 
Lexington.  The  specimens  were  collected  by  Dr.  Peter 
himself  and  the  phosphate  layer  was  reported  by  the 
quarryman  to  be  as  much  as  1  foot  thick.  The  rock  is 
described  as  being  somewhat  friable,  of  a  bluish  gray 
color,  but  brownish  gray  on  the  wreathered  surfaces,  as 
containing  many  microscopic  marine  univalve  shells  and 
as  adhering  strongly  to  the  tongue.  The  phosphates  in 
this  limestone  were  found  to  contain  as  much  as  31.815 
per  cent,  of  the  weight  of  the  rock  of  phosphoric  acid, 
which  is  equivalent  to  69.452  per  cent,  calcium  phos- 
phate. 

*Ky.  Geol.  Survey,  Chemical  Analyses  A,  Part  I.,  1890,  p.  246.  Ky. 
Geol.  Survey,  Chemical  Analyses  A,  1877,  pp.  65-66.  Also  described  as 
Vol.  4,  new  series,  Reports  Geol.  Survey  of  Ky.,  pp.  65-66. 

12 


The  composition  of  the  sample  was  as  follows : 

Analysis  of  the   Fayette  County  Phosphate   Rock,  Dried  at  212°   F. 

Phosphoric   acid,   lime,   magnesia,   alumina,   and   iron 

oxide 85.270 

Calcium  fluoride  not  est 

Carbonate  of  lime  9.180 

Carbonate   of   magnesia   .371 

Silica  and  insoluble  silicates  4.780 

Alkalies,  organic  matter,  etc.,  not  estimated 3.99 

100.00 

In  his  observations  on  this  rock,  Dr.  Peter  makes 
the  significant  statement  "the  subject  is  worthy  of 
further  investigation,  especially  in  view  of  the  agricul- 
tural and  commercial  value  of  the  phosphate  for  use 
as  fertilizers.  As  is  well  known,  the  abundant  phosphates 
of  the  rock  substratum  is  one  of  the  main  causes  of  the 
great  and  durable  fertility  of  our  blue  grass  soil  so-called, 
as  well  as  of  the  superior  development  of  the  animals 
reared  and  nourished  on  its  products." 

At  the  time  the  specimen  of  phosphatic  limestone 
whose  analysis  is  given  above  was  collected,  the  quarry 
was  not  in  use  and  the  statement  that  the  layer  of  rich 
phosphatic  rock  was  as  much  as  a.  foot  thick  could  not 
be  verified.  When  the  quarry  was  again  opened  and 
worked  for  turnpike  material  in  1877,  a  more  complete 
examination  was  made  by  Dr.  Peter  with  the  following 
results : 

Phosphatic    Limestone    From    the    McMeekin    Quarry,    Northwest   Side 

of    Newtown   Turpike,   3    Miles    North    of   Lexington,   Taken 

From  Irregular  Layers  About  1   Foot  in  Thickness. 

Composition    Dried    at  212°    F. 

Lime    carbonate 49.160 

Magnesia  carbonate  .090 

Phosphates,  with  AIX^FeAi,  etc.  (containing  21.018  per 

cent,  phosphoric  acid)  46.540 

Siliceous    residue 2.820 

Organic  matter  and  loss  1.390 


100.000 


13 


The  analyses  given  above  and  others  indicated  an  ir- 
regular distribution  of  phosphate,  and  so  11  other 
samples  were  selected  from  portions  of  the  phosphatic 
layer.  The  quantity  of  phosphoric  acid  (PoO.-,)  in  these 
11  samples  varied  from  5.053  per  cent,  to  21.940  per 
cent.,  and  averaged  15.89(3  per  cent.,  pointing  to  an  ir- 
regular distribution  and  an  irregular  local  origin. 

Interest  in  the  occurrence  of  phosphate  rock  and 
phosphatic  limestone  in  Kentucky  did  not  develop  at 
once,  or  at  least  lead  to  further  field  exploration  or  in- 
vestigation. The  discovery  and  the  commencement  of 
work  in  the  Tennessee  phosphate  field  in  1894-1895  quick- 
ened interest  in  phosphate  rock  deposits  in  general.  The 
association  of  calcium  phosphate  layers  at  the  top  of 
the  so-called  Tienton  limestone  near  Lexington  with  cer- 
tain organic  remains  was  pointed  out  by  A.  M.  Miller 
as  early  as  February,  1896.*  During  the  summer  of  1904, 
Miller  was  engaged  in  field  work  for  reports  on  the  geo- 
logy of  Jessamine,  \Voodford  and  Franklin  counties. 
These  reports,  except  that  for  Franklin  County,  were 
never  published,  but  in  that  on  "YToodford  County  he  re- 
ferred to  the  phosphate  deposits  and  their  exceptional 
richness  at  the  top  of  the  so-called  Trenton  in  the  terri- 
tory between  Midway  and  Versailles. 

In  a  report  by  the  former  director  of  the  Kentucky 
Geological  Survey,  Charles  J.  Norwood, f  it  is  stated 
that  "Professor  Miller  discovered  the  exact  representa- 
tive of  the  rock  phosphate  beds  of  Mt.  Pleasant,  Tennes- 
see, some  examples  running*  as  high  as  72  per  cent,  phos- 
phate, and  having*  definitely  differentiated  them,  he  was 
able  to  trace  them  over  considerable  areas."  Thus  the 
fundamental  studies  made  by  Professor  Miller  entitle 
him  to  the  credit  of  suggesting  the  possibilities  of  this 
region  as  the  site  of  potentially  important  phosphate 
rock  deposits.  $ 

*Miller,  A.  M.  The  association  of  the  gastronod  e-enus  cvclora  with 
phosphate  of  lime  deposits.  Am.  Geol.,  Vol.  XVII.,  1896,  pp.  74-76. 

fKy.  Geol,  Survey  Kept,  on  'the  progress  of  the  survey  for  the  years 
1904-1S05,  pp.  25-26. 

tit  has  been  stated  that  in  the  summer  of  1915,  a  negro  while  digging- 
post  holes  on  the  farm  of  H.  L.  Martin,  near  Midway,  discovered  what  he 
considered  nhosphate  rock,  similar  to  the  brown  phosphate  rock  in 
Tennessee.  Mr.  Martin  verified  the  negro's  oninion.  See  Gardner,  James 
H.,  Min»s  and  Minerals,  November-.  1912.  p.  207:  Waggaman,  W.  H.,  U.  S. 
Dept.  of  Agriculture,  Bureau  of  Soils,  Bull.  No.  81,  Marcli  20,  1912,  p.  24. 


14 


THE  PHOSPHATE  ROCK. 

TYPE  OF  BOCK. 

Phosphate  rock  occurs  in  a  variety  of  ways  and  has 
been  designated  by  a  variety  of  names  in  the  different 
states  where  found.  The  Ordovician  phosphate  rock  of 
central  Kentucky  belongs  entirely  in  a  class  known  as 
brown  phosphate  rock,  first  so-called  in  middle  Tennes- 
see. It  occurs  as  a  distinctly  laminated  residual  deposit, 
al^o  as  filling  solution  cavities  or  pockets  in  a  more  or 
less  phosphatic  limestone.  (See  Plates  V.  and  VI.  and 
Figure  4.) 

The  rock  itself  occurs  in  porous  or  loosely  coherent 
plates  and  whore  exposed,  naturally  or  artificially,  these 
plates  vary  in  thickness  from  the  very  thinnest  up  to 
those  a  few  inches  thick.  The  more  massive  rock  is  re- 
ferred to  as  lump,  plate,  or  hard  rock.  The  latter  may 
also  occur  in  thick  heavy  slabs  of  several  inches,  or  even 
a  foot  or  moie  in  thickness.  This  massive  type  is  not 
common  in  Kentucky.  It  was  observed  in  a  natural  ex- 
posure on  the  Louisville  Southern  Railway  near  the 
Cahill  place,  about  a  mile  and  a  half  west  of  Lexington 
and  on  the  Harkness  estate  (Walnut  Hall)  east  of  Cane 
Bun  and  near  the  Fayette-Scott  county  line  in  the  north- 
east nart  of  the  Georgetown  quadrangle.  Doubtless  it  is 
found  in  many  other  places  that  were  not  seen. 

Usually  the  plates  or  slabs  are  separated  from  each 
other  by  layers  of  loosely  cemented  or  porous  material 
consisting  of  phosphate  rock  in  a  fine  state  of  division 
mixed  with  more  or  less  clay.  The  explanation  of  this 
form  of  rock  will  be  made  clear  under  descriptions  of 
origin.  The  material  is  termed  phosphate  muck  and  is 
found  between  individual  plates,  especiallv  in  fresh  ex- 
posures or  drill  holes.  Muck,  or  the  soft  mixture  of 
phosphate  and  clay,  often  is  found  just  above  the  lime- 
stone on  which  the  phosphate  rock  stratum  rests. 

There  is  also  another  form  of  brown  rock  known  as 
phosphate  sard,  some  of  which  is  very  rich  in  cilcium 
phosphate  and  is  therefore  of  commercial  value.  Mix- 
tures containing  varying  proportions  of  plate  rock,  sand 
rock,  and  muck  constitute  what  is  included  under  the 
term  brown  phosphate  rock. 

The  color  of  the  rock  varies  from  a  drab  through  a 
grayish  and  yellowish  brown  to  a  deep  brown  or  almost 

15 


black.  The  muck  layers  so  often  found  overlying  the 
limestone  at  the  bottom  of  the  numerous  holes  drilled  by 
the  writer,  are  usually  nearly  black,  and  in  some  cases 
it  was  thought  that  the  dark  color  might  be  due  to  the 
presence  of  hydrous  oxides  of  manganese  which  are  a 
very  common  constituent  of  the  soils  in  the  blue  grass 
region.  The  thickness  of  the  beds  will  be  described  under 
mode  of  occurrence. 

MODE  OF  OCCURRENCE. 

Brown  rock  phosphate  deposits  depending  on  their 
manner  of  occurrence,  have  been  designated  as  "blanket" 
and  "collar"  deposits/*  The  latter  have  also  been  called 


Fig.  2. 

Blanket  phosphate  deposit  on  low,  flat  hill.     Showing  the  development 
of  "horses"  and  "cutters." 


Fig.   3. 

"Collar"  or  "run"  phosphate  deposits  formed  on  steep  hillside. 

"hat  band"  or  "rim"  deposits.  The  name  suggests  the 
character  of  the  formation.  The  term  "blanket"  applies 
to  the  nearly  horizontal  deposits  of  considerable  areal 
extent,  while  those  designated  "hat  band"  or  "rim" 
occur  within  a  limited  vertical  zone  on  the  hillsides.  (See 
Figures  2  and  3.)  The  character  of  the  deposits  depends 

*Hayes,    C.  W.,   U.   S.   Geol.   Survey,   Folio  No.  95,   1903,   pp.  5-6. 

1G 


on  the  topography  or  lay  of  the  land;  and  it  is  obvious 
that  the  blanket  deposits  are  the  most  extensive,  and 
with  other  conditions  the  same,  are  the  most  valuable. 
It  is  also  obvious  that  there  cannot  be  any  sharp  or  ar- 
bitrary division  between  blanket  and  collar  deposits,  but 
that  the  one  type  may  merge  imperceptibly  into  the 
other. 

At  the  old  workings  of  the  Central  Kentucky  Phos- 
phate Company,  the  predecessor  of  the  United  Phosphate 
&  Chemical  Company,  near  Wallace,  there  are  good  il- 
lustrations of  the  collar  type  merging  into  the  lolanket 
type  of  deposit.  The  workings  here  are  not  very  exten- 
sive, at  least  not  enough  to  indicate  to  one  who  has 
not  prospected  the  area,  whether  the  deposits  cover  the 
entire  hill  where  wrork  has  been  done  and  hence  belong 
strictly  to  the  blanket  type.  The  drilling  done  in  the 
course  of  this  investigation,  and  the  information  gathered 
from  talking  with  land  owners  who  are  acquainted  with 
conditions  from  local  drilling,  seems  to  indicate  that  the 
deposits  belong  to  both  the  collar  and  blanket  types,  and 
that  the  former  are  probably  the  more  numerous. 

It  was  stated  above  that  the  type  of  the  deposits 
depends  on  the  topography.  The  topography  in  this  part 
of  Kentucky  is  gently  undulating,  or  rolling.  A  study  of 
it  shows  clearly  that  it  has  resulted  from  the  dissection, 
or  cutting  down  of  a  gently  sloping  surface  which  orig- 
inally was  more  than  1050  feet  high  in  the  southeastern 
part  of  the  Georgetown  quadrangle,  and  more  than  850 
or  900  feet  high  in  the  northwestern  corner.  Such  topog- 
raphy affords  the  best  conditions  for  the  formation  of 
residual  phosphate  deposits,  providing  the  other  requi- 
site conditions  are  fufilled.  The  Lockport  quadrangle 
to  the  northwest  furnishes  an  example  where  geological 
conditions  are  similar  to  those  in  the  Georgetown  quad- 
rangle, but  where  the  topography  is  such  as  to  preclude 
the  possibility  of  the  formation  of  phosphate  rock  de- 
posits owing  to  its  rugged  character,  except  at  the  very 
outcrop.  It  follows,  therefore,  that  the  economic  im- 
portance of  such  deposits  should  be  slight. 

The  phosphate  rock  deposits  are  always  associated 
with  limestone  and  it  is  from  a  phosphate  bearing  lime- 
stone that  they  are  considered  to  be  derived.  The  orig- 
inal phosphatic  material  occurs  in  definite  bands  in  the 

17 


limestone  mixed  with  calcium  carbonate.  (See  Plate  VII.) 
It  is  believed  without  much  doubt  that  these  highly  phos- 
phatic  bands  are  original,  and  that  they  were  laid  down 
alternately  with  bands  of  limestone  containing  less  phos- 
phate, or  none  at  all. 

With  the  leaching  of  the  limestone  the  insoluble 
phosphate  rock  and  the  other  insoluble  materials  orig- 
inally present,  which  are  chiefly  clay,  silicified  fossils, 
and  chert  debris,  have  slumped  down  slowly  onto  the 
underlying  limestone.  The  capping  of  clay  has  resulted 
from  the  similar  changes  which  have  taken  place  in 
higher  clay  bearing  or  argillaceous  limestone  beds.  In 
the  writer's  opinion  no  other  theory  or  hypothesis  is  re- 
quired to  explain  the  formation  of  the  phosphate  de- 
posits. Solution  has  taken  place  along  joint  planes  more 
rapidly  than  in  the  other  places  and  has  led  to  the 
formation  of  so-called  "cutters"  or  "horses."  (Plate 
IX.)  Horses  are  the  limestone  masses  projecting  into 
the  phosphate  rock  layers,  the  latter  of  which  curve  over 
them  in  arches,  as  will  be  observed  from  the  illustrations 
(Plates  V.  and  X.)  and  in  the  cutters  between  the 
horses  the  phosphate  rock  deposits  often  show  abnormal 
thickness  from  the  mechanical  slumping  down  from  the 
flanks  of  the  horses.  (Figure  4.)  This  behavior  of  the 
phosphate  rock  leads  to  great  variations  in  the  thickness 
of  the  deposits  and  necessitates  most  thorough  prospect- 
ing before  the  average  thickness  over  a  given  area  can 
be  closely  estimated.  Splendid  examples  of  the  irregular 
limestone  surface  underlying  the  phosphate  rock  are  to 
be  seen  at  the  old  workings  near  Wallace  (Plate  IX.), 
and  in  sections  at  many  quarries  in  the  region,  among 
which  may  be  mentioned  the  Haggin  quarry  at  Elmen- 
dorf,  east  of  Maysville  pike;  the  Stark  quarry  on  the 
Versailles-Midway  pike;  the  James  P.  Headley  quarry 
just  outside  of  Lexington  city  limits  and  east  of  the 
Russel  Cave  pike,  and  doubtless  at  many  other  quarries 
over  the  entire  region. 

Actual  exposures  of  limestone  and  overlying  phos- 
phate are  not  very  common.  The  mode  of  occurrence, 
therefore,  cannot  be  studied  as  closely  as  desirable  from 
the  commercial  point  of  view  from  either  outcroppings  or 
quarries.  Drilling  operations  and  the  digging  of  pits 
are  necessary  to  throw  the  maximum  light  on  the  mode 

18 


I    .    1. 


r- 


r^-r 


t  .  1  "J 


T      r~r 


i  .  .1 


iLS     I 


>.  I   .  r 


"_;•" '•  t  ''^^j^g^m'lg 


Fig.   4. 
C— Clay -seam.     S— Soil.    L.S.— Limestone.   J — Jointing.   P— Phosphate. 

DEVELOPMENT  OF  CUTTERS. 

Scale — 1  inch=20  feet  approximately. 

Showing  the  development  of  cutters  after  J.  S.  Hook, 

"The  Resources  of  Tennessee." 
Vol.  IV,  No.  2.    April,  1914.     P.  64. 


of  occurrence.    The  former  method  of  prospecting  will 
be  described  under  the  proper  heading. 

The  overburden  of  the  phosphate  rock  consists,  as 
has  been  stated,  chiefly  of  clay  mixed  with  different  ma- 
terials like  chert  debris,  silicined  fossil  remains,  etc.  This 
overlying  soil  contains  small  quantities  of  lime  phos- 
phate. The  following  section  was  measured  on  the  Louis- 
ville Southern  Railway  near  the  Cahill  place  already 
referred  to  as  about  1V>  miles  northwest  of  Lexington: 

Section   of   Phosphate   Rock  on   the   Louisville   Southern    Railway   Near 
the  Cahill   Place,  1'/2  to  2  Miles  Northwest  of  Lexington.  . 

4' .Overburden. 

3'       6"     Massive   phosphate   rock. 

3'       9"     Clay. 

3'       6"     Limestone  and  blue  shale. 

A  sample  of  the  overburden  gave  less  than  2  per 
cent,  phosphoric  acid.  A  sample  of  overburden  from 
station  No.  11,  near  Hulett's,  gave  less  than  1  per  cent, 
phosphoric  acid.  A  sample  collected  from  a  thickness  of 
S1/^  feet  in  excavating  for  a  telephone  pole  at  the  road- 
side :>4  of  a  mile  northwest  of  Hillenmeyer  Station,  gave 
less  than  2  per  cent,  phosphoric  acid.  Though  the  over- 
burden contains  but  little  phosphate,  its  possibilities  as 
a  filler  in  making  commercial  fertilizer  ought  not  to  be 
lost  sight  of,  for  it  is  this  soil  that  renders  the  blue  grass 
region  so  productive. 

The  abundance  of  iron  and  manganese  oxide  con- 
cretions in  the  soil  overlying  the  phosphate  rock  is  worth 
remarking.  A  notable  quantity  of  these  concretions  oc- 
curs near  Station  No.  11,  or  Hulett's,  on  the  interurban 
trolley  line  between  Lexington  and  Nicholasville.  Here 
a  layer  of  the  concretions  3  feet  thick  was  observed.  The 
top  soil  in  the  entire  blue  grass  region  is  shot  through 
with  manganese  concretions,  usually  of  small  size.  These, 
no  doubt,  were  originally  disseminated  in  the  limestone 
and  have  been  segregated  during  the  process  of  weather- 
ing. 

The  presence  of  manganese  is  of  interest  since  it  has 
been  considered  to  have  some  fertilizer  value.  An 
elaborate  series  of  experiments  has  been  carried  on  by 
the  Bureau  of  Soils,  IT.  S.  Department  of  Agriculture, 

20 


having  in  view  the  determination  of  the  effect  of  man- 
ganese salts  on  grain  and  vegetable  growth.  Both  pot 
and  field  tests  were  made  and  the  conclusion  was  reached 
that  crop  growth  in  unproductive  sandy  loam  was  stimu- 
lated by  the  addition  of  5  to  50  parts  of  manganese  to 
a  million  of  soil,  whereas  no  effects  were  noticeable  when 
a  productive  loam  soil  was  used.  In  some  tests  an  actual 
decrease  in  yield  was  attributed  to  the  addition  of  man- 
ganese salts.* 

DISTRIBUTION  AND  CHARACTER  OF  THE  PHOSPHATE 

BEDS. 

A  somewhat  restricted  district  in  the  vicinity  of 
AVallace  a  few  miles  south,  southeast,  and  southwest 
of  Midway,  Woodford  County,  is  the  only  one  of  promi- 
nence within  which  phosphate  rock  is  known  to  occur 
to  any  great  extent.  Between  Midway  and  Spring  Sta- 
tion, along  the  Louisville  and  Nashville  Railroad,  and 
on  certain  farms  to  the  north  of  the  railroad,  is  another 
area  where  phosphate  rock  has  been  found  in  some 
quantity.  The  limits  of  these  areas  have  not  been  very 
accurately  determined,  but  enough  drilling  has  been  done 
to  indicate  that  locally,  very  important  deposits  of  phos- 
phate rock  should  be  expected.  When  it  is  recalled  that 
brown  rock  phosphate  may  be  expected  to  run  from  600 
to  1,000  tons  per  acre  per  foot  of  thickness,  small  acre- 
ages may  prove  of  great  importance  if  the  phosphate 
deposits  are  thick  enough  and  of  good  quality. 

In  the  fields  and  districts  named  there  are  many 
small  areas  in  which  the  phosphate  bed  is  lacking,  or  too 
thin  to  be  of  value,  or  perhaps  is  overlain  by  a  cover  too 
thick  to  remove  profitably.  Some  prospecting  has  been 
done  throughout  all  the  areas  and  the  distribution  of 
the  phosphate  is  quite  well  known  in  certain  tracts.  The 
work  has  been  done  privately,  and  hence  the  records  are 
not  available.  As  an  example  of  the  quantity  of  phos- 
phate rock  occurring  in  this  region,  it  has  been  told  the 
writer  that  16,000  to  18,000  tons  of  phosphate  rock  were 
produced  from  a  five-acre  tract  at  "Wallace,  that  is  to 
say  an  average  of  3,600  tons  per  acre.  It  has  also  been 
stated  that  1,200  to  1,400  tons  per  acre  foot  are  found 

i  rer,   J.   J.   and  Sullivan,   M.  X.    The  action  of  manganese  in  soils, 
U.    S.    Dept.    of   Agriculture,    Bull.    42,    32  pages,    1914. 

21 


in  this  region,  and  the  excess  over  that  usually  occurring 
in  the  Tennessee  brown  rock  field  is  due  to  the  greater 
hardness  and  density  of  the  Kentucky  rock  as  compared 
with  that  in  Tennessee.  For  the  accuracy  of  these  figures 
and  statements  the  writer  cannot  vouch. 

Outside  of  the  Wallace  area  and  that  to  the  west  of 
Midway,  phosphate  rock  is  known  to  occur  in  and  around 
Lexington,  Fayette  County.  Phosphate  rock  deposits  are 
also  known  in  the  vicinity  of  Georgetown,  Scott  County, 
near  the  Forks  of  Elkhorn,  Franklin  County,  near  Ver- 
sailles, Woodford  County,  and  near  Pine  Grove  Station, 
Clark  County.  The  results  obtained  from  prospecting 
in  these  different  areas  are  outlined  beyond  and  com- 
ments made  as  appears  necessary. 

In  this  report  the  Wallace  area  will  be  understood 
to  include  the  area  between  Midway  on  the  north  and 
Versailles  on  the  south,  with  Wallace  as  a  geographical 
center.  It  will  comprise  the  territory  between  South 
Elkhorn  Creek  on  the  east  and  an  indefinite  boundary 
west  of  the  Versailles  and  Midway  pike.  It  was  near 
Wallace — a  short  distance  to  the  east  of  it  and  near  the 
Georgetown- Versailles  branch  of  the  Southern  Railway 
—that  the  first  phosphate  of  the  Kentucky  field  was  mined 
and  sold.  The  low  rolling  topography  of  this  region  af- 
fords ideal  conditions  for  the  development  of  commercial 
phosphate  deposits,  assuming  its  original  presence  in  the 
limestone.  The  region  is  also  notably  fertile  and  in  the 
district  along  the  Midway- Versailles  pike  the  name  "as- 
paragus bed"  of  the  blue  grass  region  has  been  applied, 
owing  to  its  marked  degree  of  fertility. " 

The  following  sections,  together  with  the  map,  show 
the  general  distribution  of  the  phosphate  rock  together 
with  its  character,  variations,  and  composition  as  deter- 
mined chiefly  by  prospecting  with  the  drill. 

All  sections  and  analyses  numbered  100  or  over  re- 
fer to  drill  records  and  the  samples  obtained  from  them. 


22 


SECTIONS   AND  ANALYSES  OF   PHOSPHATE   ROCK. 
Wallace  District. 

No.     8.     Central   Kentucky   Phosphate   Co.,    y2    mile   east   of  Wallace 

Crossroads,  Woodford   County,  Ky. 
No.     9.     Central   Kentucky  Phosphate   Co. 
No.  10.     Central  Kentucky  Phosphate   Co. 
No.  11.     Central    Kentucky    Phosphate    Co. 
No.  12.     Central    Kentucky    Phosphate    Co. 
No.    8— 

4  y2 ' — Overburden. 

2V2'— Phosphate  rock,  59.78%  Ca3(PO4)2. 

Limestone. 
No.    9— 

6 y2 ' — Overburden. 

4'     — Phosphate  rock,  65.25%Ca,(PO4)2. 

Limestone. 
No.   10— 

iy2' — Overburden. 

21/2' — Phosphate    rock,    71.88%    Ca3(PO4)2. 

Limestone. 
No.  11— 

6'  to  7' — Overburden. 

2'-7"— Phosphate  rock,  72.86%  Ca3(PO4)2. 

Limestone. 
No.  12— 

12'  to  13' — Overburden. 

5 '-7"— Phosphate  rock,  72.85%   Ca3(PO4)2. 

Limestone. 

No.     20.     R.    S.   Stark   quarry,   east   side  Versailles-Midway   pike,   3% 
miles  southwest  of  Midway,  Ky. 

2'-4' Overburden. 

2' Phosphate  rock,  66.48%   Ca3(PO4)2. 

Limestone. 

No.     22.     R.   S.   Stark  quarry,   east   side  Versailles-Midway   pike,   3^ 
miles   southwest  of   Midway,    Ky. 

5' Overburden. 

4' Phosphate  rock,  58.55%   Ca3(P04)?. 

Limestone. 
No.     23.     Clinton  M.  Hawkins  farm,  3  miles  southwest  of  Midway,  or 

y2  mile  south  of  Wallace,  Woodford  County. 
1'      6"     Overburden. 

1'       6"     Phosphate  rock,   59.88%   Ca3(PO4)2. 
Limestone. 

23 


No.  100.     S.  C.  McKinnivan  estate,  1  mile  southeast  of  Wallace. 

10' Clay  overburden  with  chert. 

1' Phosphate. rock,  containing  17.79%   Ca^PO,),. 

Limestone. 
No.  104.     S.  C.  McKinnivan  estate,  1^4  miles  southwest  of  No.  100. 

7'..... .Clay. 

2'       1"     Low   grade    phosphate    rock. 

6'       3"     Phosphate  rock,  lower  part  of  which  is   brown  phos- 
phate muck. 
Limestone. 
Analyses- 
No.  104.     2'     1"  layer.    31.86%   Ca:i(P04),. 
No.  104A.     Highest    grade    material    in    drilling.      53.47%    C'a:t 

(PO,),. 

No.  104B.     Muck  from  lower  part  of  drilling.  49.04%  Ca3(PO4):,. 
No.  101.     Will  Steele's  estate,  south  side  Frankfort  and  Lexington  pike, 

114  miles  southeast  of  Wallace. 
1'     10"     Clay. 

0-8"     Phosphatic  Clay. 
3'       9"     Phosphate   rock,   48.46%    Ca3(PO4),. 

Limestone. 
No    102.     Will  Steele's  estate,  14   mile  south  of  No.  101. 

3'       4"     Clay. 
10'       4"     Phosphate   rock,   48.06%    Ca,(PO4),. 

Limestone. 

A  grab  hand  sample  selected  from  the  core  drilled  showed  48.18% 
Ca3(Po4)2. 

No.  103.     Will  Steele's  estate,  ^  mile  west  of  No.  101. 
4'       5"     Clay. 
2'       2"     Phosphatic  clay  and  low  grade     f    Upper  2'  2",  53.47% 

phosphate Ca3(P04)3. 

5"     Phosphate  rock  I    Lower  5",   65.16% 

Limestone.  Ca3(P04),. 

No.  105.     R.  S.  Stark  estate,  1%  miles  southeast  of  Wallace,  north  of 

Frankfort  and  Lexington  pike. 
2'      7"     Clay. 

2' Phosphate  rock  containg  sand  and  clay,  becoming  clay 

at  base,  31.49%  Ca3(PO4)2. 
2'     11"     Clay. 

Limestone. 

No.  106.     R.  S.  Stark  estate,  %  mile  north  of  No.  105. 
6'       5"     Clay. 

No  phosphate  rock. 
Limestone. 
No.  107.     R.  S.  Stark  estate,  %  mile  northwest  of  No.  105. 

4"      6"    Phosphate  rock 5  Upper  half'  42'92%   Ca'(PO')" 

Limestone.  <Lower  hal('  23'80% 

24 


No.  108.     Estate  of  the  late  Mrs.  Margaret  Murray,  1%  miles  southeast 
of  Wallace  and  north  of  Frankfort  and  Lexington  pike. 

9' Clay. 

7'       8"     Phosphate  rock. 

2' Clay  and  some  phosphate. 

Limestone. 

Three  different  grades  of  phosphate  rock  came  from  this  drilling 
containing  31.47%,   41.46%,  and   63.87%    Ca.CPOJ,,  the   latter  from  a 
2'  10"  layer  overlying  the  2'  clay  bed. 
No.  109.     Estate  of  the  late  Mrs.  Margaret  Murray,  %  mile  northwest 

of  No.   108. 
2'     10"     Clay. 
1'       5"     Chert. 
1'     10"     Clay  and  chert. 
3'       6"     Phosphate  rock. 

Limestone. 

Two  different  grades  of  phosphate  rock  came  from  the  hole,  con- 
taining 54.48%  and  54.06%  of  Ca3(PO4),. 
No.  110.     Estate  of  the  late  Mrs.  Margaret  Murray,  1%   miles  east  of 

Wallace,  near  corner  of  farm. 
11'       4"     Clay. 

4' Low   grade   phosphate   rock. 

Limestone. 

Two  different  grades  of  phosphate  rock  came  from  the  hole,  con- 
taining 21.30%   and   30.40%   Ca,(PO4)2. 
No.  111.     Estate  of  the  late  Mrs.  Margaret  Murray,  580  feet  south  of 

No.  110. 
3'       5"     Clay. 

2' Phosphate  rock. 

Limestone. 

Three  different  grades  of  phosphate  rock  came  from  the  hole,  con- 
taining 20.30%,  37.62%,  and  20.43%  Ca3(PO4)2. 
No.  112.     Henry  L.  Martin  estate,   %   mile  east  of  Wallace,  north  of 

Frankfort-Lexington  pike. 
8'       9"     Clay. 
2'       9"     Phosphate  clay. 
3'       2"     Phosphate  sand,  50.30%  Ca3(P04)2. 
3'       9"     Sand  and  plate  rock,  60.87%  Ca3(PO4)2. 

Limestone. 

No.  114.     H.  L.  Martin,  Jr.  estate,  %  mile  south  of  house. 
1'     11"     Clay  with  phosphate  rock  at  base. 
4"     Phosphate  rock,  25.78%   Ca3(PO4)2. 

Limestone. 

No.  115.     Gate  to  H.  L.  Martin,  Jr.  estate,  l1/^  miles  southwest  of  Mid- 
way. 

12'       8"     Clay. 

4'       2"     Phosphate  rock,   37.43%    Ca3(PO4)2. 
Limestone. 

25 


No.  116.     H.  L.  Martin,  Jr.  estate. 
5'     11"     Clay. 

3'       1"     Phosphatic  sand,  35.16%   Ca3(PO4)2. 
3'       9"     Clay  and  phosphate  rock,  44.30%  Ca3(PO4)2. 
3'       1"     Phosphate  sand  and  plate  rock,  56.50%  Ca3(PO4)2. 

Limestone. 
No.  118B.     H.  L.  Martin,  Jr.  estate,  %  mile  south,  15°  E.  from  the  rail- 

road   crossing. 
2'       7"     Clay. 

11"     Phosphate  rock,  56.19%   Ca3(PO.4)2. 

Limestone. 

No.  119.     H.  L.  Martin,  Jr.  estate. 
6'       2"     Clay. 
2'       1"     Phosphate  rock,  43.53%   Ca3(PO4)2. 

Limestone. 
No.  120.     H.  L.  Martin,  Jr.  estate,  N.  10°  E.  from  the  house. 

WT     11"     Phosphate  rock  ......   \  Upper  3'     °"'  28'92%  <*•<«>.),. 

Limestone.  1  Lower  4'  U*    40'62%  Ca< 

No.  121.     H.  L.  Martin,  Jr.  estate. 
5'       1"     Clay. 

3"     Phosphate  rock,  40.19%  Ca3(PO4),. 

Limestone. 

No.  122.     H.  L.  Martin,  Jr.  estate,  %  mile  northeast  of  No.  121. 
4'       4"     Clay. 
3'       5"     Phosphate  rock,   50.20%   Ca3(P04)2. 

Limestone. 

No.  123.     H.  L.  Martin,  Jr.  estate,   %   mile  southeast  of  house. 
o'        Q"     Clav 


3-      3"    Phosphate  rock  .......  \  U<">er  r     £  31'06% 

Limestone.  I   Lower  r  10  '  22'20%  Ca»<PO'>" 

No.  124.     H.  L.  Martin,  Jr.  estate,  east  of  Versailles  and  Midway  pike, 

about  %  mile  southwest  of  Midway. 
8'       6"     Clay. 
6'       3"     Phosphate  rock;  lower  4'  7"  gave  34.38%  Ca3(P04)2. 

Limestone. 

No.  125.     H.  L.  Martin,  Jr.  estate. 
5'       9"     Clay. 

2"     Phosphate  rock,  24.36%   Ca3(P04)2. 

Limestone. 

No.  126.     James  J.  Nugent,  just  northeast  of  Wallace  crossroads. 
7'       5"     Clay. 
11'      9"     Phosphate  rock. 

Limestone. 

The  three  grades  of  phosphate  rock  from  this  drilling  ran  as  fol- 
lows: Phosphate  sand  8",  31.96%;  phosphatic  clay  3'  2",  43.34%;  and 
phosphate  rock,  T  2",  54.25%  Ca3(PO4)2. 

26 


No.  127.     Nugent  Bros,  estate,  y2  mile  south  of  Wallace  crossroads. 
8'  ...Clay. 

V      3"    Phosphate  rock  ........  .(  U™er  4'  10"'  45'00%  Ca.(PO.),. 

Limestone.  (  Lower  3'    5"'  65'92%  Ca»<PO<),. 

No.  128.     A.  T.  Harris  estate,  1%  miles  southeast  of  Wallace. 
4'       5"     Clay. 
1'  ..............  Phosphate  rock,  47.32%   Ca3(PO4)2. 

Limestone. 

No.  129.     A.  T.  Harris  estate. 
3'       7"     Clay. 
1'       3"     Phosphate  rock,  58.86%   Ca3(P04)2. 

Limestone. 
No.  130.     A.  T.  Harris  estate,  just  west  of  house. 

8'  ......  3"""  Phosphate  rock  ......  \  V™er  S'    7"'  40'61%  Cas(PO<);. 

Limestone.  I   Lower  4'     8"'  64'74%   Ca,<PO.),. 

No.  131.     A.  T.  Harris  estate,  %  mile  west  of  house. 
'   6'  ..............  Clay. 

2'       5"     Phosphate  rock,  39.21%  Ca3(PO4)2. 

Limestone. 
No.  132.     E.  L.  Lillard  estate,  2y2  miles  southeast  of  Midway  near  South 

Elkhorn  Creek. 
4'  ........  Clay. 


........ 

4'      9"    Phosphate    rock  .....   <  Upper    2'  r'>   45'13%    CMPOJ, 

Limestone.  (  Lower  2'    8"'  36'27%  Ca,,(PO4)=. 

No.  133.     E.  L.  Lillard  estate,  %  mile  west  of  No.  132. 
7'       6"     Clay. 

4'       2"     Phosphatic  clay,  24.56%   Ca3(PO4)2. 
3'       2"     Phosphatic  sand  and  plate  rock,  36.78%  Ca3(P04)2. 
3'       3"     Phosphatic  sand  and  plate  rock,  48.34%  Ca3(P04)2. 

Limestone. 

No.  134.     E.  L.  Lillard  estate,  %  mile  northwest  of  No.  133. 
3'      4"     Clay. 
5'       2"     Phosphate  rock,  33.11%  Ca3(P04)2. 

Limestone. 

No.  136.     E.  L.  Lillard  estate,  3  miles  southeast  of  Midway. 
3'       6"     Clay. 

3"     Phosphate  rock,  52.23%  Ca3(PO4)2. 

Limestone. 
No    138.     E.  L.  Lillard  estate,  %  mile  west  of  Zion's  Hill  near  South 

Fork  of  Elkhorn. 
3'  ..............  Clay. 

1'       4"     Phosphate  rock,  39.82%   Ca3(P04)2. 
5'  ..............  Phosphatic  clay,  15.82%   Ca3(P04)2. 

Limestone. 


27 


No.  137.     J.  B.  Sellers  estate,  2  miles  southeast  of  Midway  near  high- 

way. 

8'  Clay. 

...... 


6'       2"     Phosphate  rock  ......  (    V™*r   V     5"'  48'67%  Cas(PO4)2. 

Limestone.  \   Lower  4'     9"'  37'69%  Ca»(PO4)2. 

No    144.     R.  S.  Stark  estate,  just  east  of  Versailles-Midway  pike,  iy2 

miles  southwest  of  Wallace,  opposite  old  quarry. 
8'       1"     Clay. 
14'       4"     Phosphate    rock,    50.77%    Ca3(PO4),. 

Limestone. 

No.  145.     R.   S.   Stark  estate,   25   feet  west  of  hole  No.   144. 
3'       5"     Clay. 
V       2"     Phosphate   rock,   71.64%    Ca3(PO4)a. 

Limestone. 
No.  146.     R.  S.  Stark  estate,  l1^  miles  south  of  Wallace,  near  Southern 

R.  R. 

5'       7"     Clay. 
1'       5"     Low  grade  phosphatic  material,   41.32%    Ca,(PO4)o. 

Limestone. 

No.  147.     R.  S.  Stark  estate,  %  mile  southeast  of  No.  146. 
1'     10"     Clay. 

2'       8"     Phosphate  rock,   57.06%   Ca:((P04)2. 
1'       6"     Clay  and   chert. 
4'       2"     Clay. 

Limestone. 

No.  148.     R.  S.  Stark  estate,  y2  mile  northeast  of  No.  147. 
2'       2"     Clay. 

3'       3"     Phosphate  rock,   53.10%    Ca3(P04)2. 
8'  ........  Dark  brown  clay,  29.50%  Ca^PO,),. 

Limestone. 
No.  150.     Lister  Witherspoon,  iy2  miles  southwest  of  Wallace  and  west 

of  Versailles-Midway  pike. 
4'       5"     Clay. 

3'       1"     Containing   some    phosphatic   sand   merging   into   clay 
at  base,  23.26%   Ca3(P04)2. 
Limestone. 

No.  156.     Lister  Witherspoon  estate,  rear  of  residence. 
5'       6"     Clay. 
1'       4"     Phosphate  sand  and  clay;  this  and  the  2'  1"  layer  be- 

low gave  16.11%  Ca3(P04)2. 
11"     Cherty  material  passing  into  clay  gumbo. 
2'       1"     Phosphate  rock  and  clay. 

Limestone. 

No.  151.     McBrayer  Moore  estate,  1  mile  southwest  of  Wallace. 
6'     10"     Clay. 

No  phosphate  rock. 
Limestone. 

28 


No.  152.     George  McLeod  estate,  2%  miles  southwest  of  Wallace. 
2'       5"     Clay. 

8"     Containing  some  phosphate  sand,  no  analyses. 

Limestone. 

No.  155.     George  McLeod  estate,  in  front  of  house  near  sink  hole. 
15'       4"     Clay. 
2'       3"     Phosphate  sand,  33.55%  Ca3(P04)2. 

Limestone. 
No.  159.     Estate  of  Thomas  Dunlap,  3  miles  S.  B.  of  Wallace,  north  side 

of  Frankfort  and   Lexington  pike. 
2'       2"     Clay. 
1'       4"     Phosphate  muck,  33.09%   Ca3(P04)2. 

Limestone. 

A  sample  of  phosphate  rock  collected  from  a  3'  6"  bed  exposed  in 
excavating  a  barite  vein  near  gate  to  farm  gave  52.49%   Ca.  (PO4)2. 
No.  161.     Estate  of  Wm.  A.  Dunlap,  2V,  miles  S.  E.  of  Wallace,  near 

South  Elkhorn  Creek. 
1'     11"     Clay,  the  lower  part  of  which  contains  phosphate  rock 

fragments. 

1'       6"     Clay  and  some  fragments  of  high  grade  phosphate  rock. 
1'     11"     Phosphate  muck,  probably  low  grade,  35.45%  Ca:;(PO4)2. 

Limestone. 

No.  162.     Estate  of  Wm.  A.  Dunlap,  2  miles  east  of  Wallace. 
3'     10"     Clay. 

1'       7"     Fine  phosphate  sand. 

3'       4"     Phosphate  muck  and  phosphate  sand,  42.01%  Ca.CPOJo. 
4'       5"     Low  grade  clay. 
Limestone. 

District   West  of    Midway. 

No.  142.     Estate  of  Mrs.  Chas.  Nuckols,  1%  miles  northwest  of  Midway. 
4'     10"     clay. 
1'       6"     Phosphate  rock. 

Limestone. 

The  two  grades  of  phosphate  rock  from  this  hole  gave  52.43%  and 
48.16%  Ca3(P04)2. 

No.  143.     Estate  of  Mrs.  Chas.  Nuckols,  14  mile  north  of  No.  142. 
8'       8"     Clay. 

4' Phosphate  and  clay,  rather  low  grade,  37.56%  Ca;.(P04)2. 

2'       2"     Phosphate  sand,  51.13%   Ca3(P04)2. 

Limestone. 

The  two  grades  of  phosphate  rock  from  this  hole  gave  37.56%  and 
51.13%  Ca.,(P04)2. 
No.  139.     E.  L.  Davis  estate,  Rookwood  Station,  on  L.  &  N.  R.  R.,  1% 

miles  N.  W.  of  Midway. 
2'      2"     Clay. 

V     10"     Phosphate  rock,  40.35%  Ca3(P04)2. 
Limestone. 

29 


No.  140.     E.  L.  Davis  estate,  %  mile  N.  E.  of  No.  139,  on  railroad. 
5'       3"     Clay. 
4'       3"     Phosphate  rock  and  sand,  64.30%   Ca3(PO4),. 

10"     Clay  and  plate  rock,  37.90%   Ca3(PO4)2. 
1'       8"     Clay. 

Limestone. 

No.  141.     E,  L.  Davis  estate,  on  L.  &  N.  R.  R.,  in  small  sink  y2  mile 
S.  W.  of  No.  139. 

11' .Clay. 

4'       8"     Phosphate  rock j   U^er   *''  35'21%  Ca3(P04)2. 

Limestone.  (   Lower  6">  56'41%  Ca3(P04), 

No.  163.     Chas.  Thomas  estate,  2y2  miles  N.  W.  of  Midway. 
11'     11"     Clay. 
1'       4"     Black  muck. 
2'       2"     Sandy   phosphate,   carries   38.22%    Ca3(PO4),. 

2' Black  muck,  carries  50.75%  Ca:;(PO4)2. 

1'       8"     Fine  black  muck  and  sand. 

Limestone. 

No.  164.     Chas.  Thomas  estate,  y2  mile  S.  W.  of  No.  163. 
4'       5"     Clay. 
1'       9"     Phosphate  rock,  carries  46.37%    Ca3(Po4),. 

Limestone. 
No.  166.     Chas.  Thomas  estate,  north  of  Leestown  pike,  *4  mile  S.  W. 

of  No.  165. 
11'       2"     Clay. 

1'       7"     Low  grade  phosphate,  carries  32.20%  Ca3(P04),. 
4'       6"     Clay  with  a  few  inches  of  phosphate  sand. 

Limestone. 
No.  169.     On  the  south  side  of  the  highway,  between  the  highway  and 

the  L.  &  N.  Railroad,  y2  mile  east  of  Spring  Station. 
7'       9"     Clay. 
5'       4"     Phosphate  rock,  carries  43.14%   Ca3(PO4),. 

Limestone. 
No.  170.     Estate  of  Mrs.  Harry  Wise,  just  north  of  house,  %  mile  N.  E. 

of  Spring  Station. 
3'       5"     Clay. 

2'       5"     Containing     disseminated      phosphate     muck,     carries 
58.12%  Ca3(P04)2. 
Limestone. 

No.  171.     Estate  of  Mrs.  Harry  Wise,  %  mile  northeast  of  No.  170. 
5'       4"     Clay. 

4' Phosphate   muck,   carries   31.37%    Ca3(PO4)2. 

Limestone. 
No.  172.     Estate   of   Dr.    Samuel   A.    Blackburn,    %    mile   northeast   of 

Spring  Station. 
10'       3"     Clay. 

1'       7"     Phosphate   rock,    carries    38%    Ca3(PO4)2. 
Limestone. 

30 


No.  173.     South  side  of  Leestown  pike,  3  miles  northwest  of  Midway. 
10'       4"     Overburden. 

5'       9"     Low  grade  phosphate  muck  and  clay;   lower  part  con- 
tains 31.78%  Ca3(P04)2. 
Limestone. 
No.  174.     Estate  of  Mrs.  Annie  Slack,  2y2  miles  northwest  of  Midway, 

south  side  Lexington  pike. 
4'       2"     Clay. 

3'       5"     Phosphate  rock,  upper  2'  8",  contains  44.15%  Ca3(PO4)2. 
Limestone. 

Frankfort  District. 

No.  175.     Estate  of  Judge  E.  C.  O'Rear,  3y2  miles  east  of  Frankfort. 

5' Clay. 

1'       9"     Low  grade  phosphate  rock,  contains  45.41%  Ca3(PO4),. 

Limestone. 

Note. — A  hand  sample  of  phosphate  chips  collected  at  the  gate  to 
the  estate  of  Judge  E.  C.   O'Rear  gave  70.65%   Ca3(PO4),. 

Several  drill  holes  put  down  on  different  parts  of  the  estate  were 
found  to  contain  no  phosphate  rock. 

No.  182.     Estate  of  Judge  T.  H.  Painter,  6  miles  N.  E.  of  Frankfort, 
north    of    South    Elkhorn    Creek. 

2' Clay. 

1'       8"     Phosphate  rock  5Upper  8"  contained  32-42%  Ca3(PO4),. 
Limestone.  (Lower  V  contained  43.67%  Ca3(P04)2. 

No.  188.     Estate  of  Judge  T.  H.  Painter,  5%  miles  east  of  Frankfkort, 

just  north  of  the  South  Fork  of  Elkhorn  Creek. 
2'       2"     Clay. 
2'       7"     Phosphate   rock,   carries   53.98%    Ca3(PO4)2. 

Limestone. 

Several  drill  holes  put  down  on  different  parts  of  the  estate  were 
found  to  contain  no  phosphate  rock. 

iiul'n.,', 

Forks  of  Elkhorn  District. 

No.  191.     Estate  of  South  Trimble. 

Scattering  fragments  of  phosphate  rock  in  this  drill  hole  yielded 
56.79%  Ca3(PO4),. 

A  few  other  drill  holes  on  this  estate  gave  no  phosphate  rock. 
No.  192.     Estate  of  George  Hannon,  5%  miles  N.  E.  of  Frankfort,  near 

gate  at  entrance  to  estate. 
5'       9"     Clay. 

1'     10"     Fine   phosphate   sand    and     rock,     containing    41.86% 
Ca3(P04)2. 
Limestone. 


31 


Lexington   District. 

No.  13.  J.  B.  Haggin  estate  (Elmendorf)  :  Quarry  on  estate,  %-% 
mile  east  of  Maysville  pike. 

3' Overburden. 

2'       6"     Phosphate  rock,  51.40%  Ca:i(PO4)2. 

Limestone. 

No.  27,  28,  29.  Southern  Railway  (Louisville  &  Lexington  line)  near 
Cahill  place,  iy2  miles  west  of  Lexington. 

4' Overburden    (clay  and   soil). 

3'       6"     Massive  phosphate  rock. 
3'       9"     Clay. 

Limestone. 

No.  27.  Top  4'  of  soil  less  than  2%  Ca3(P04)2.  This  indicates  in  a 
general  way  what  may  be  expected  in  the  top  soil  of  this 
region. 

No.     28.     Chip  from  the  3'  6"  bed:    53.15%   Ca3(P04)a. 
No.     29.     Sample  of  the  3'  9"  bed  which  may  be  considered  phosphatic 

clay.    16.44%   Ca3(PO4)2. 

No.  33.  James  P.  Headley  estate,  east  side  Russell  Cave  pike,  just 
outside  Lexington  city  limits. 

8' Overburden    (clay  and  soil). 

5' Phosphate   rock,   35.14%   Ca:1(PO4),. 

Limestone. 

No.  34.  Station  No.  11,  near  Hulett's,  interurban  railway,  between 
Nicholasville  and  Lexington,  Ky. 

5' Overburden. 

3' Chiefly   maganese    and    iron    oxide    concretions.     Less 

than  1%  Caa(PO4)2. 

10' Clay. 

5' Massive  phosphate  rock,  upper  4  feet  carries   30.98% 

Ca3(PO4)2. 

No.  40.  R.  W.  Higgins  quarry,  1V2  miles  northwest  of  Greendale, 
Fayette  County. 

1' Overburden. 

3' Phosphate  rock,  29.79%   Ca3(P04)2. 

Limestone. 
No.  218.     Estate  of  Judge  Jas.  H.  Mulligan,  N.  E.  of  Lexington,  between 

L.  &  N.  R.  R.  and  Russell  Cave  pike. 
5'     10"     Clay. 
1'       3"     Phosphate  rock,  containing  49.18%  Ca3(P04),. 

Limestone. 
No.  218A.     Estate  of  Judge  Jas.  H.  Mulligan,  W.  of  No.  218,  but  E.  of 

railroad. 
8'       2"     Clay. 

4'       3"     Phosphate  rock,  containing  45.06%   Ca3(PO4)2. 
Limestone. 


32 


No.   219.     Estate  of  Judge  Jas.  H.  Mulligan,  E.  of  point  where  Russell 

Cave  pike  crosses  L.  &  N.  R.  R. 
4'       3"     Clay. 
1'       5"     Phosphate    rock,    containing    39.91%    Ca:,(PO4),. 

Limestone. 

No.  194.     Just  east  of  Mentelle  Park,  Lexington.  (No  analysis.) 
1'       4"     Phosphate  sand. 

Limestone. 

(Note:      Overburden   has   been  scraped   away   here   to   obtain   clay 
for  brick.) 

No.   195.     20  feet.  E.   of  No.   194. 
5'       3"     Clay. 

2' Phosphate  rock,  containing  31.44%  Ca;,(PO4),. 

Limestone. 

No.   193.     25  feet  E.  of  No.  195. 
2'     10"     Clay. 
5'       6"     Phosphate    rock,    containing    30.04%    Ca3(P04)2. 

Limestone,  overlain  by  a  thin  layer  of  worthless  yellow- 
clay. 

No.  197.     25  feet  E.  of  No.  196.    (No  analysis.) 
3'       3"     Overburden. 
4'     11"     Phosphate  sand  and  clay. 

1' Clay. 

Limestone. 
No.  198.     Estate   of   H.    G.   McDowell,   southeast   of   Lexington   on   the 

Richmond  pike. 
8'       7"     Clay. 
7'       1"     Phosphate  rock,  lowest  5  ft.,  carried  48.64%  Ca3(PO4),. 

Limestone. 
No.  199.     Estate  of  J.  D.  Clark,  3y2  miles  N.  W.  of  Lexington. 

No  phosphate. 
No.  200      Estate  of  J.  D.  Clark,  %  mile  S.  E.  of  No.  199. 

4'       4"     Clay   overburden   with   some   disseminated   phosphatic 

sand  near  base. 
8'     11"     Phosphate  muck,  containing  37.56%  Ca:!(PO4)v, 

Limestone. 

No.  201.     Estate  of  J.  D.  Clark,  %  mile  N.  W.  of  house. 
6'     10"     Overburden. 

8'       6"     Phosphate    sand,    muck,    and    some    phosphate    rock, 
containing  30.93%   Ca3(PO4)2. 
Limestone. 
No.  202.     Estate  of  J.  W.  Coleman.  N.  of  Lexington,  between  Newtown 

and  Russell  Cave  pikes. 
4'       7"     Clay. 

2'       2"     Phosphate  sand,  carries  22.78%   Ca:i(PO4),. 
2'       3"     Barren  Clay. 
Limestone. 

33 


No    203.     Estate  of  J.  W.  Coleman,  N.  of  Lexington,  between  Newtown 

and  Russell  Cave  pikes. 
4'       2"     Clay. 

2'       8"     Phosphate     sand     and    lump    rock,     carries     49.25% 
Ca,(P04)2. 
Limestone. 

No.  204.     Estate  of  Ernest  Erdman,  N.   of  Lexington  and  E.  of  New- 
town   pike.    (No    sample.) 
1'       5"     Clay. 
l'-2'       6"     A  mixture  of  clay  and  phosphate  rock  fragments. 

Limestone. 
No.  206.     Estate  of  P.  P.  Bradley,  N.  of  Lexington  and  E.  of  Newtown 

pike.     (No    sample.) 
1'       3"     Clay. 

1'       1"     Phosphate  rock   in   scattering   fragments. 
1'       3"     Clay. 

Limestone. 
No.  207.     Estate  of  P.  P.  Bradley. 

4' Clay. 

9"     Some  phosphate  rock. 
3'     11"     Barren  clay. 
1'       4"     Phosphate  rock,  containing  45.13%   Caa(POJ2. 

Limestone. 

No.  208.     Estate  of  P.  P.  Bradley. 
5'     10"     Overburden. 
4'       8"     Phosphate  rock,  containing  48.51%   Ca:i(PO4),. 

Limestone. 
No.  211.     Estate   of   Capt.    J.    D.    Yarrington,    between    Maysville    and 

Russell  Cave  pikes. 
5'      1"     Clay. 

7"     Containing   some    phosphate    rock,    containing    45.74% 
Ca3(P04)2. 
Limestone. 

No.  212.     Estate  of  Capt.  J.  D.  Yarrington. 
6'     10"     Clay. 

2' Low  grade  phosphate  rock,  carrying  20.54%  Ca3(P04)o. 

5'       6"     Clay  with  1'  phosphate  rock  at  base. 

Limestone. 
No.  213.     Mr.  Easton  estate,  N.  E.  of  Lexington,  W.  of  Maysville  pike. 

2' Clay. 

2'       8"     Phosphatic  sand,  containing  less  than  5%  P2O5. 
2'      2"     Clay  mixed  with  a  little  phosphate. 

Limestone. 
No    214.     Estate  of  Judge  George  B.  Kinkead,  N.  E.  of  Lexington,  just 

E.  of  Russell  Cave  pike. 
3'      8"     Clay. 

4"     Fine  lump  rock,  containing  40.79%  Ca3(P04)2. 
Limestone. 

34 


No.  214A.     Estate  of  Judge  George  B.  Kinkead,  about  50  feet  further 

south  on  the  hillside  from  No.  214. 
2'       5"     Clay. 
1'      6"     Phosphate  rock    (no  sample). 

Limestone. 

No.  214A.     Estate  of  Mrs.  Martha  Withers,  northeast  outskirts  of  Lex- 
ington. 

2'      2"     Clay. 

2'       1"     Containing    phosphate    in    lower     1-2',     with     34.11% 
Cas(P04)2. 
Limestone. 
No.  216.     On  the  Russell  Cave  Pike,  N.  80°  W.  of  Mrs.  Martha  Withers' 

estate. 
5'       6"     Clay. 

7"     Phosphate  rock,  no  analysis. 

Limestone. 
No.  217.     Estate  of  Mrs.  Martha  Withers,  E.  side  of  the  estate  near 

Maysville  pike. 
2'      1"     Clay. 
1'       4"     Phosphate  rock. 

(Note:     Struck  water  in  this  hole  and  did  not  get  to  bottom.   No 
sample.) 

No.  217A.     Estate  of  Mrs.  Martha  Withers,  nearer  the  Maysville  pike. 
1'     10"     Clay. 

9"     Phosphate  rock,  carrying  24.31%   Ca3(PO4)2. 

Limestone. 

No.  221.     Estate  of  H.  Gibson  heirs,  S.  W.  of  Lexington. 
17'       3"     Clay. 

Limestone. 

(Note:     About  15'  black  muck  in  the  lower  part  of  the  hole.   Low- 
est  3-5'   contained   21.06%    Ca3(P04)2. 
No.  223.    A.  M.  Miller  estate,  rear  of  house,  South  Limestone  Street, 

Lexington. 

6'      7"     Reddish  brown   clay. 
4'      3"     Phosphate  sand  and   clay,   30.93%   Ca3(PO4)2. 

7"     Clay   chiefly,    but   with   some   phosphate   sand. 
2'      4"     Barren    clay. 

Limestone. 

No    224.     Estate   of   A.    M.    Miller,    S.   W.    of   No.    223. 
6'       3"     Clay. 

6'      4"    Chiefly  clay,  with  some  phosphate  sand,  no  analysis. 
1'      2"     Phosphate  sand. 

Limestone. 

No.  226.     Kentucky  Agricultural  Experiment  Station  grounds. 
5'      7"     Clay. 

7"     Disseminated  phosphate  sand  with  heavy  chert. 
4|"    Variegated  clay  and  rotten  chert. 

Limestone. 
(Note:     No  sample.   No  phosphate  rock.) 

35 


No.  227.     Kentucky  Agricultural  Experiment  Station  grounds,  %   mile 

S.  W.  of  No.  226  along  the  road. 
6'       1"     Clay. 

8"     Phosphate  sand. 

4'       4"     Low  grade  phosphate  sand  and  clay. 
2'       2"     Barren  clay. 

9"     Phosphatic   muck   and   yellow   clay,   containing  35.10% 

Ca3(P04)2. 

1'       8"     Yellow  drab  clay. 
2'     9£"     Clay  and   heavy  chert. 

Limestone. 
No.  228.     Estate  of  Joe  C.  Van  Meter,  S.  of  Lexington,  and  W.  of  Tates 

Creek  pike. 
8'       4"     Clay. 

Limestone. 
No  phosphate  rock. 
No.  229.     Estate  of  Joe  C.  Van  Meter,  S.  of  Lexington  and  W.  of  Tates 

Creek  pike. 
5'     11"     Clay. 

8' Iron   manganese  concretions. 

Limestone. 

Two  characteristics  stand  out  above  all  the  others 
in  the  sections  given  above,  these  are  the  great  varia- 
tion in  thickness  and  composition  of  the  phosphate  rock. 
This  is  characteristic  of  the  entire  brown  rock  phosphate 
area.  To  obtain  a  better  idea  of  the  composition  of  the 
different  grades  of  rock  it  would  have  been  desirable  to 
wash  each  sample  as  drilled,  thereby  separating  muck> 
sand,  and  lump  rock.  This  is  done  in  practice  in  prepar- 
ing the  mined  rock  for  market  for  conversion  to  acid 
phosphate.  It  could  not  be  done  by  the  writer  in  the 
field  without  much  inconvenience.  Tha  analyses  of  the 
hand  specimens  of  lump  or  plate  rock  throw  some  light 
on  what  might  be  expected  from  the  lump  rock  in  the 
sections,  and  where  the  specimens  were  collected  and  their 
analyses  compared  with  a  few  of  those  of  the  lump  rock 
itself  selected  from  the  drillings,  the  results  show  fairly 
close  agreement. 

LOCALITIES  TO  BE  PROSPECTED. 

It  must  not  be  inferred  that  all  the  promising  locali- 
ties in  the  blue  grass  region  have  been  examined  and 
prospected,  for  such  is  not  the  case.  The  co-operative 

36 


work  earned  on  by  the  United  States  and  Kentucky 
Geological  Surveys  was  limited  by  the  available  funds, 
and  it  is  known  that  prospecting  by  private  parties  has 
been  carried  on  in  otjier  areas  and  which  without  doubt 
has  yielded  results  which  may  be  as  promising  or  much 
more  so  than  those  obtained  in  this  investigation.  In  a 
cut  on  the  Louisville  and  Nashville  Railroad,  within  the 
town  of  Versailles,  beyond  the  iron  bridge  one-eighth 
of  a  mile  west  of  the  concrete  highway  bridge,  samples 
were  collected  from  probably  the  Woodburn  member 
since  colmnwuia  halli  was  observed.  Of  three  samples 
collected  one  gave  27.14  per  cent.,  another  (No.  25)  gave 
73.30  per  cent.,  and  a  third  yielded  20.84  per  cent,  cal- 
cium phosphate.  The  selected  chips  in  sample  No.  25 
indicate  what  the  lump  rock  may  run  in  this  region. 
South  of  Versailles,  on  the  west  side  of  the  Nicholas- 
ville  pike,  on  the  farm  of  Ball  brothers,  chips  were  noted 
in  abundance  on  parts  of  the  farm,  especially  in  the 
rear  of  a  group  of  small  cabins.  The  samples  collected 
here  gave  a  79.49  per  cent,  calcium  phosphate.  To  the 
northwest  of  Versailles,  where  the  Midway  pike  leaves 
the  trolley  line,  a  sample  collected  near  the  Fishback 
place  yielded  76.23  per  cent,  calcium  phosphate.  Other 
analyses  of  selected  samples  not  included  in  the  tables 
above  are  given  below.  It  should  be  remembered  that 
these  are  selected  hand  samples  of  chips  which  represent 
lump  rock  alone  and  not  the  run  of  a  drill  hole  or  pit. 

SELECTED    SPECIMENS    OF    PHOSPHATE    CHIPS. 
Wallace    District. 

Per  Cent,  of 

Phosphate  of  Lime. 

Ca3(P04),. 

No.   47   61.53 

No.   48   ..  76.12 

No.   49   ..  64.03 

No.   50   12.37 

No.   51   80.67 

No.   52   77.47 

No.   56   77.64 

No.  47.  R.  S.  Stark  estate,  1%  miles  south  of  Wallace,  at  side  of 
private  roa<J  through  farm.  Taken  from  the  bottom  of  a  post  hole. 

No.  48.  Locality  same  as  No.  47.  Selected  chips  from  a  pile  of 
phosphate  rock  thrown  out  in  excavating. 

37 


No.  49.  Mrs.  M.  Murray's  estate.  Sample  collected  from  the  bottom 
of  an  old  prospect  pit  just  west  of  the  house,  1%  miles  east  of  Wallace. 

No.  50.  Mrs.  M.  Murray's  estate,  iy2  miles  east  of  Wallace.  Chips 
collected  from  surface.  Thrown  out  in  making  an  excavation  in  the 
northeast  corner  of  the  farm  near  road. 

No.  51.  Thomas  Dunlap  estate,  2y2  miles  southeast  of  Wallace, 
near  South  Elkhorn  Creek,  in  rear  of  house  and  barn;  south  hillside  of 
a  small  branch  shown  on  the  map. 

No.  52.  William  Steele  farm,  about  2  miles  southeast  of  Wallace. 
Chips  thrown  out  in  digging  an  old  phosphate  pit. 

No.  56.  E.  L.  Lillard  farm.  Fragments  collected  %  mile  north- 
east of  the  main  gate  at  the  entrance  to  the  mansion. 

SELECTED   SPECIMENS    OF    PHOSPHATE    CHIPS. 

Lexington    District. 

Per  Cent,  of 

Phosphate  of  Lime. 

Ca.(P04),. 

No.     1 48.59 

No.   15 71.91 

No.   32   71.14 

No.  41  57.25 

No.  42   73.34 

No.  1.  Brown  lump  rock,  cut  in  the  Louisville  Southern  Railway 
near  the  Cahill  farm,  2  miles  northwest  of  Lexington,  between  the 
Frankfort  and  Versailles  pikes. 

No.  15.  Main  Street,  Lexington.  Fragments  of  supposed  phos- 
phate rock  from  a  sewer  excavation  nearly  opposite  Kaufman's  cloth- 
ing store. 

No.  32.  Rear  of  the  plant  of  the  Lexington  Power  Company,  just 
west  of  North  Limestone  Street  about  a  mile  from  the  center  of  the 
city. 

No.  41.  On  the  Lexington-Richmond  turnpike  within  the  city 
limits,  at  the  end  of  East  Main  Street,  about  100  yards  east  of  Mentelle 
Park. 

No.  42.  About  1  mile  south  20°  east  of  Ashland,  former  home  of 
Henry  Clay.  The  material  was  selected  from  that  thrown  out  in  ex- 
cavating for  a  pumping  station. 

SELECTED   SPECIMENS   OF   PHOSPHATE   CHIPS. 

Georgetown  District. 

Per  Cent,  of 

Phosphate  of  Lime. 

Ca3(P04)2. 

No.  18  48.97 

No.  43  70.26 

38 


No.  18.  L.  V.  Harkness  estate  (Walnut  Hall),  about  ll/2  miles  due 
north  of  Lexington.  Massive  type  of  phosphate  rock. 

No.  43.  Fred  S.  Crunbaugh  estate,  near  North  Elkhorn  Creek, 
about  2y2  to  3  miles  east  of  Georgetown,  Scott  County. 

SELECTED   SPECIMENS    OF    PHOSPHATE    CHIPS. 

Forks  of   Elkhorn   District. 

Per  Cent,  of 
Phosphate  of  Lime. 

Ca3(P04)2. 
No.   44  72.98 

No.  44.  G.  L.  Hannen  farm,  4^  miles  east  of  Frankfort,  south 
side  of  the  pike,  at  the  side  of  the  lane  going  into  the  farmhouse. 


SELECTED   SPECIMENS    OF    PHOSPHATE    CHIPS. 

Pine  Grove  Station,  Clark  County. 

Per  Cent,  of 

Phosphate  of  Lime. 

Ca3(P04)2. 

No.  53  71.50 

No.  54 40.88 

No.  53.  Sample  overlying  limestone  a  few  hundred  feet  east  of 
Pine  Grove  Station  and  on  the  opposite  side  of  the  railroad. 

No.  54.  Material  from  place  above  the  limestone  a  few  paces 
east  of  where  the  surface  chips  constituting  No.  53  were  collected. 

It  follows  from  the  analyses  of  hand  samples  col- 
lected in  various  localities  where  systematic  prospect- 
ing with  the  drill  was  not  carried  on,  that  several  areas 
will  bear  further  close  examination.  Northwest  of  Ver- 
sailles between  the  Midway  pike  and  the  trolley  line  to 
the  west  of  it,  the  type  of  topography  is  a  promising 
index  and  the  region  seems  to  have  undergone  the  deep 
weathering  necessary  to  the  development  of  the  phos- 
phate rock  deposits.  All  the  low  flat  hills  in  this  region 
are  comprised  in  part  in  the  geologic  horizon  of  the  phos- 
phate rock  and  the  latter  should  not  be  too  deep  for 
profitable  mining,  provided  it  proves  to  be  of  sufficiently 
high  grade.  This  is  a  region  which  should  be  closely  pros- 
pected, for  example  in  the  neighborhood  of  the  George 
Fishback  and  the  Senator  Camden  places. 

39 


According  to  Professor  Miller,  good  phosphate  rock 
should  be  found  on  both  sides  of  the  Elkhorn  Creek,  that 
is  between  the  Lexington-Georgetown  pike  on  the  east 
and  the  Lexington-Frankfort  pike  on  the  west.  But  little 
is  known  of  any  phosphate  occurrences  in  this  general 
area  north  of  the  Leestown  pike. 

The  region  around  Hulett's,  on  the  trolley  line  be- 
tween Lexington  and  Nicholasville,  is  one  which  so  far 
as  known  has  never  been  thoroughly  or  even  superficially 
prospected.  It  might  prove  to  be  worth  going  over  to 
make;  sure  that  no  important  phosphate  rock  deposits 
are  overlooked. 

Other  localities  where  prospecting  might  yield  re- 
sults are  in  the  vicinity  of  the  Forks  of  Elkhorn,  Frank- 
Jin  County;  near  Georgetown,  Scott  County,  and  in  the 
vicinity  of  Danville,  Boyle  County.  The  analysis  of  a 
smnple  found  near  Pine  Grove  Station,  Clark  County, 
given  above  is  also  of  interest.  The  region  about  Done- 
rail,  Fayette  County,  is  also  worth  attention.  In  a  study 
like  that  carried  on  by  the  writer,  it  was  impossible  to 
prospect  over  every  promising  region,  and  only  careful 
work,  will  reveal  the  possibilities  of  the  different  sec- 
tions  of  the  blue  grass  region. 

METHODS  OF  PROSPECTING. 

In  beginning  this  investigation  rock  hand  samples 
were  selected  at  natural  or  artificial  exposures.  It  was 
soon  found  that  such  samples  mean  little  or  nothing  in 
arriving  at  an  adequate  idep  as  to  the  real  commercial 
character  of  the  deposits.  For  this  reason  systematic 
prospecting  with  the  drill  was  undertaken.  The  closeness 
with  which  the  latter  was  carried  on  may  be  observed 
from  the  map.  It  will  be  appreciated  that  in  a 
government  investigation  prospecting  could  not  be 
cai'ried  on  as  closely  as  it  would  have  been  by  private 
parties  planning  to  determine  tonnage  in  restricted  areas 
with  the  view  of  operating.  The  methods  employed  under 
similar  conditions  in  Tennessee  are  outlined  further  on. 
From  the  methods  employed  in  Kentucky  and  the  close- 
ness with  which  the  wrork  was  done,  a  good  idea  is  ob- 
tained, where  the  best  deposits  may  be  expected  and 
where  further  development  work  ought  to  be  carried  on. 
Even  with  the  most  up-to-date  methods  of  prospecting, 

40 


perfectly  representative  samples  are  difficult  to  get.  It 
is  doubtful  whether,  owing  to  the  difficulty  of  properly 
apportioning  the  lump  and  muck  rock,  the  content  in 
calcium  phosphate  of  the  material  can  be  represented 
in  any  hand  sample. 

In  the  Wallace  area  many  hand  samples  were  collect- 
ed and  more  than  50  holes  were  drilled.  In  but  compara- 
tively few  of  the  holes  was  no  phosphate  found  at  all. 
The  limestone,  however,  outcrops  very  near  the  surface 
in  places  and  leaves  no  room  for  any  deposits  to  form, 
or  if  it  ever  was  present,  it  lias  been  removed  by  erosion. 
Toward  the  creek  bottoms  generally  no  deposits  were 
encountered  and  approaching  the  hilltops  or  900-foot 
contour,  the  overburden  grows  heavy  and  the  deposits 
thin.  The  richest  deposits  were  found  generally  between 
840  and  860  feet  in  elevation.  The  sections  given  above 
for  the  individual  farms  show  the  great  variation  in  the 
thickness,  character,  and  position  of  the  phosphate  rock 
encountered. 

The  methods  employed  in  this  investigation  for 
prospecting  for  phosphate  rock  in  central  Kentucky 
were  in  part  those  commonly  employed  in  the  brown 
phosphate  rock  fields  of  Tennessee.  Only  drilling  with 
augers  was  employed  in  Kentucky.  Prospecting,  of 
course,  could  not  be  carried  on  so  extensively  as  by 
private  parties.  Prospecting  on  an  extensive  scale  is 
expensive,  and  can  only  be  done  by  those  companies  or 
land  owners  who  plan  to  ascertain  definitely  the  work- 
ability or  non-workability  of  a  given  area.  It  is  carried 
on  in  different  ways,  or  by  a  combination  of  different 
methods. 

One  of  the  common  methods  of  prospecting  for 
brown  rock,  which  may  be  employed  in  general  tor  all 
soft  and  easily  penetrated  sedimentary  deposits,  where 
the  overburden  is  also  soft  and  not  too  thick,  is  by  means 
of  an  ordinary  4-inch  earth  auger  handled  by  two  men. 
Three-quarter-inch  pipe,  in  convenient  lengths,  may  be 
screwed  together  as  the  auger  descends  to  furnish  the 
necessarv  additional  length  of  pipe.  The  auger  is  pro- 
vided with  a  T-handle  to  make  it  easv  to  bring  the  re- 
quired pressure  to  bear.  Where  it  is  difficult  to  penetrate 
the  formation,  as  where  much  chert  is  present,  a  4-iuch 
post  hole  digger  may  be  used.  This  is  merely  a  hollow 

41 


form  of  drill  or  cylinder  about  10  or  12  inches  long,  pro- 
vided with  a  slit.  Samples  are  removed  with  comparative 
rapidity  with  these  two  tools,  and  the  auger  or  digger 
is  easily  emptied  after  their  load  of  material  has  been 
loosened  by  a  cheap  screwdriver.  The  work  is  carried 
on  quite  rapidly  and  the  sample  representing  the  phos- 
phate bed  is  next  treated  as  described. 

The  entire  sample  was  spread  on  a  piece  of  oil  cloth 
and  thoroughly  mixed  in  the  usual  way.  It  was  then 
quartered  and  the  two  opposite  quarters  discarded.  This 
treatment  was  repeated  until  a  final  small  portion  was  ob- 
tained which  was  in  turn  sampled  by  selecting  portions 
from  it  here  and  there.  The  final  sample,  which  was  about 
four  pounds  in  weight,  was  then  sacked  and  sent  to  the 
laboratory.  In  certain  cases  where  the  original  drill 
sample  was  very  large,  more  than  one  sample  may  have 
been  selected  and  where  the  material  from  a  drill  hole 
consisted  of  definite  layers  of  lump  rock,  sand,  and  muck, 
the  attempt  was  made  to  secure  representative  samples 
of  each  of  these  different  varieties. 

In  ordinary  blanket  deposits  it  is  the  custom  in 
Tennessee  to  sink  the  drill  holes  about  200  feet  apart  in 
squares ;  but  in  rim,  collar,  or  hat  band  deposits  the  holes 
are  spaced  200  feet  apart  throughout  the  length  of  the 
deposit  and  from  50  to  200  feet  apart  on  their  short 
axes. 

In  conjunction  with  drill  holes,  test  pits  have  to  be 
sunk  where  the  prospecting  is  done  with  proper  care. 
A  pit  is  dug  every  400  feet  to  obtain  samples  for  re- 
covery or  washing  tests.  Such  samples  are  much  better 
than  those  obtained  by  drilling  for  they  represent  what 
may  be  expected  from  actual  mining  operations.  By 
washing  such  material,  the  quantity  of  lump  rock,  sand, 
and  muck  may  be  measured  and  their  composition  or 
content  in  bone  phosphate  may  be  determined.  The  re- 
covered products  are  dried,  weighed,  and  analyzed  sep- 
aratelv  and  the  percentages  of  recovery  calculated. 
Konwing  the  weight  of  a  cubic  foot  of  the  material  in 
the  ground,  the  percentage  of  recovery  may  be  converted 
into  such  convenient  terms  as  an  acre  foot  of  recoverable 
material,  that  is  the  quantity  recoverable  per  acre  per 
each  foot  of  depth  (43,560  cubic  feet). 

It  is  estimated  that  the  cost  of  prospecting  averages 

42 


7  to  T1/^  cents  per  foot  of  hole  with  augers,  or  $1.50  to 
$2.00  per  acre  for  average  conditions. 

Especial  care  is  required  to  determine  the  average 
thickness  of  most  areas  where  the  rock  is  known  to  lie 
in  cutters.  The  phosphate  rock  may  constitute  from  30 
to  50  per  cent,  of  the  total  volume  below  the  top  of  the 
limestone  table. 

The  samples  from  prospecting  are  prepared  for 
analyses  by  washing  in  an  ordinary  wash  tub.  The  sand 
is  saved  by  decantation  and  the  lump  is  separated  by 
the  aid  of  a  hose  and  an  eight-inch  slotted  screen.  The 
recovered  products  are  dried,  weighed,  and  analyzed 
separately.  Tonnages  are  calculated  on  the  basis  of  a 
recovery  of  1,000  long  tons  of  dry  rock  per  acre  foot  for 
high  grade  deposits,  but  for  average  grades  this  will 
be  more  nearly  850  tons  per  acre  foot.  For  more  accurate 
work  the  percentages  of  recovery  should  be  used  as  de- 
termined in  the  laboratory,  allowing  15  to  20  per  cent, 
in  actual  mining  and  treatment.* 

METHOD  OF  COLLECTING  SAMPLES. 

In  collecting  the  samples  without  the  drill,  for  ex- 
ample in  the  old  workings  at  Wallace,  the  face  of  the 
workings  was  carefully  exposed  with  pick  and  shovel, 
and  a  space  was  cleared  of  debris  at  the  base  of  the 
exposures  to  be  sampled.  About  5  pounds  of  rock  were 
picked  off  from  each  foot  of  section  exposed,  care  being 
taken  to  procure  adequate  representation  of  lump,  sand, 
and  fine  muck.  The  larger  fragments  wTere  then  broken 
to  the  size  of  a  walnut  and  all  the  grades  wrere  then 
mixed,  quartered,  and  the  opposite  quarters  discarded. 
This  operation  was  repeated  until  the  two  remaining 
quarters  were  of  the  proper  size  for  analysis  and  ex- 
amination. Similar  methods  were  employed  with  the 
cores  of  phosphate  rock  obtained  in  drilling. 

THE  LOCAL  QUARRY  INDUSTRY  AS  A  GUIDE  TO 
PROSPECTING. 

Natural  exposures  are  comparatively  rare  in  this 
part  of  Kentucky,  but  many  small  quarries  have  been 
opened  in  this  region  which  are  in  most  cases  located 

*Fisrures  are  taken  from   Barr,    James  A.,    Tenn.   Phosphate  Practice., 
Amn.    Inst.,    Min.    Engrs.,    Bull.   93,    Sept.,    1914,    pp.   2397-2413. 

43 


near  the  public  highways  where  they  are  rarely  missed 
by  the  geologist.  There  is  a  reason  tor  this.  The  estates 
which  border  the  main  public  pikes  have  stone  fences 
and  the  material  entering-  into  their  construction  has 
cjme  from  a  neighborhood  quarry.  To  save  transport- 
in,;;1  the  stone  long  distances  the  quarry  is  usually  located 
near  the  highway.  An  examination  of  the  soil  overlying 
the  limestone  in  these  quarries  may  often  furnish  a  safe 
index  of  the  presence  or  absence  of  phosphate  in  a  local- 
ity. It  is  a  criterion,  however,  which  has  to  be  used  with 
care,  but  the  writer  found  it  a  help  in  indicating  the 
possible  presence  or  absence  of  phosphate  in  different 
localities.  The  difficulty  with  such  an  index  is  the  rela- 
tive scarcity  of  quarries,  and  it  becomes  a  sound  basis  of 
judgment  only  as  the  number  of  quarries  increases. 

TUP:  COMPOSITION  OF  TJIK  PHOSPHATE  ROCK. 

The  material  collected  from  the  drillings  shows 
great  variation  in  content  of  calcium  phosphate.  From 
the  method  of  collecting  the  samples  it  is  to  be  expected 
that  the  analyses  would  run  low.  In  the  Wallace  district, 
of  the  total  number  of  analyses  made  of  materials  col- 
lected from  drillings,  about  35  per  cent,  showed  a  con- 
tent of  50  per  cent,  or  more  of  calcium  phosphate.  Less 
than  10  pei-  cent,  of  the  total  showed  i  content  between 
(>()  and  70  per  cent,  and  but  5  per  cent,  of  the  total 
showed  more  than  70  per  cent.  The  latter  material  was 
for  the  most  part  collected  from  well  exposed  sections  in 
the  old  workings  of  the  Central  Kentucky  Phosphate 
CYmpany,  near  Wallace.  The  remaining  65  per  cent,  con- 
tained less  than  50  per  cent,  calcium  phosphate,  the  great 
buik  of  the  material  having  from  30  to  50  per  cent. 

The  number  of  drillings  made  in  the  other  districts 
was  not  very  large,  not  large  enough  to  base  close  esti- 
mates on.  The  results  obtained  are  outlined  below.  In 
the  area  between  Midway  and  Spring  Station,  where 
prospecting  was  carried  on,  about  25  per  cent,  of  the 
samples  obtained  in  drilling  contained  between  50  and 
60  per  cent,  calcium  phosphate,  and  about  5  per  cent,  be- 
tween 60  and  70  per  cent.  The  remaining  70  per  cent, 
contained  less  than  50  per  cent,  calcium  phosphate. 

The  great  bulk  of  the  material  collected  from  drill- 
ings in  the  vicinity  of  Lexington  contained  less  than  50 

44 


per  cent.,  wliicli  is  likewise  true  for  the  Forks  of  Elk- 
horn  district.  The  reader  may  reach  his  own  general 
conclusions  from  a  study  of  the  analyses  given  above, 
bearing  in  mind  that  all  the  sections  and  analyses  num- 
bered 100  and  more  refer  to  drill  records  and  the  samples 
obtained  from  them.  In  the  case  of  selected  specimens 
from  old  excavations  or  natural  exposures,  the  results 
are  given  elsewhere.  They  indicate  that  the  washed  lump 
rock,  which  is  virtually  what  most  of  the  latter  material 
represents,  contains  more  than  70  per  cent,  calcium  phos- 
phate in  many  localities  and  one  sample  collected  from  the 
Thomas  Dunlap  farm,  21/->  miles  southeast  of  Wallace, 
near  South  Elkhorn  Creek,  gave  80.67  per  cent,  calcium 
phosphate.  This  high  content  in  bone  phosphate  does 
not  appear  to  be  wholly  unique,  for  in  a  table  comprising 
6  analyses  Waggaman*  states  that  hard,  brown,  heavy 
plates  of  phosphate  rock  collected  on  the  Slack  farm,  3 
miles  northwest  of  Midway,  contained  81.08  per  cent, 
calcium  phosphate.  Foerstet  likewise  reports  a  sample 
running  82.37  per  cent,  calcium  phosphate  from  the  same 
farm.  It  is  probable  that  the  two  samples  were  collected 
from  the  same  pit.  Foerste  likewise  reports  a  sample 
from  the  Lister  Wither  spoon  farm,  near  the  Versailles- 
Midway  pike,  which  contained  80.80  per  cent,  calcium 
phosphate. 

Thus  it  appears  that  while  occasional  occurrences 
of  lump  rock  are  found  containing  more  than  80  per  cent 
calcium  phosphate  and  although  rock  in  workable  quan- 
tities will  be  found  running  up  to  present  commercial  re- 
quirements, that  is  containing  70  per  cent,  and  more  BPL, 
it  is  quite  safe  to  affirm  that  the  bulk  of  Kentucky  phos- 
phate rock  will  be  found  to  contain  less  than  70  per  cent. 
BPL.  This  means  that  in  the  most  promising  areas  the 
reek  will  have  to  be  carefully  washed  and  cheaply  worked 
by  the  most  modern,  labor-saving  devices  to  bring  it  up 
to  present  commercial  standards  so  that  it  may  be  able 
to  compare  with  Tennessee  rock.  Without  doubt  much 
of  the  Kentucky  rock  of  low  or  intermediate  grade  must 
wait  for  cheap  chemical  or  electrical  processes  of  con- 
centration. 


*Wa,^«aman,  W.  H.  A  report  on  the  natural  phosphate  of  Tennessee, 
Kentucky  and  Arkansas.  U.  S.  Dept.  of  Agriculture,  Bureau  of  Soils, 
Bull.  81,  p.  L'5,  1912. 

fKentucky  Oeol.    Survey,    Series   TV.,    Vol.    I.,    Pt.    I.,    1913,    pp.    431-439. 

45 


ORIGIN. 

SOURCE  OF  THE  PHOSPHATE. — The  phosphate  was  de- 
posited originally  on  the  floor  of  a  shallow  sea.  Some  of 
it  may  have  been  chemically  precipitated  directly  from 
solution,  and  some  may  have  come  from  phosphate  se- 
creting- organisms  which  flourished  in  the  water  of  the 
Ordovician  sea.  The  phosphate  probably  came  from 
both  these  sources.  Such  organisms  exist  at  the  present 
time  and  some  of  them  have  been  shown  to  have  shells 
consisting  largely  or  almost  wholly  of  calcium  phosphate. 

F.  AV.  Clarke  and  AY.  C.  "Wheeler*  have  shown  that 
the  element  phosphorus  occurs  in  abundance  in  the  shells 
of  certain  brachiopods,  crustaceans  and  alcyonarians. 
Certain  worm  tubes  are  also  notably  phosphatic-  The 
exact  original  nature  of  the  phosphates  is  not  known 
since  there  is  not  enough  basic  material  present  to  have 
formed  the  normal  tricalcium  phosphate.  Ultimately  it 
reaches  this  form  in  the  sediments.  Some  of  the  phos- 
plmtic  alcyonarian  corals  contain  from  7.95  to  13.35  per 
cent,  calcium  phosphate.  Certain  of  the  brachiopods,  es- 
pecially the  lingulas  and  glottidias,  are  highly  phos- 
phatic, containing  from  74.73  to  91.74  per  cent,  calcium 
phosphate,  and  some  of  the  phosphate  present  is  repre- 
sented as  a  magnesian  salt.  The  analyses  of  crustaceans 
given  show  a  range  of  6.57  to  27.44  per  cent,  calcium 
phosphate,  with  an  exceptional  analysis  of  a  shrimp 
shell  showing  49.46  per  cent,  calcium  phosphate.  Some 
worm  tubes  show  as  much  as  20.72  per  cent,  calcium  phos- 
phate. 

These  results  are  interesting  not  only  quantita- 
tively, but  qualitatively  as  well.  Without  doubt  even 
minute  quantities  of  calcium  phosphate  in  the  shells  of 
animals  have  an  important  geologic  and  economic  signi- 
ficance since  in  connection  with  the  formation  of  all  our 
phosphate  deposits  and  other  economic  minerals  as  well, 
the  factors  of  time  and  process  of  mechanical  concentra- 
tion are  highly  important.  Even  with  only  minute  quan- 
tities of  calcium  phosphate  originally  present,  slow  pro- 
cesses of  concentration  acting  over  long  periods  of  time 
produce  important  results. 

ORIGINAL  MODE  or  OCCURRENCE. — The  original  phos- 
phatic material  as  now  seen  in  nature,  that  is  the  phos- 

*U.    S.   Geol.    Survey  Professional  Paper  Xo.   102,   1917,    p.   50. 

46 


phatic  material  as  originally  deposited,  occurs  in  definite 
bands  in  the  limestone  mixed  with  calcium  carbonate. 
There  is  little  question  that  these  highly  phosphatic 
bands  are  original  and  that  they  were  laid  down  alter- 
nately with  bands  of  limestone  containing,  to  be  sure, 
some  phosphate,  but  essentially  less  phosphatic  than  the 
intervening  layers.  The  illustrations  taken  in  the  Mt. 
Pleasant,  Tennessee,  brown  rock  field,  in  the  Wallace, 
and  other  localities  in  Kentucky  (see  Plates  VII.  and 
VIII.)  illustrate  this  alternate  banding.  Typical  cross 
bedding  of  the  phosphate  and  calcium  carbonate  layers 
was  also  observed  at  the  Wallace  workings.  The  abund- 
ance of  the  cyclora  casts  not  infrequently  gives  the  rock 
an  oolitic  and  almost  botryoidal  appearance,  but  the  little 
rounded  particles  are  not  necessarily  true  oolites,  and 
they  are  usually  not.  The  alternating  rich  and  lean  phos- 
phate layers  thicken  and  thin  and  pinch  out  abruptly— 
in  a  word  they  have  all  the  characteristics  of  a  normal 
cross  bedded,  sedimentary  rock  deposited  where  there 
was  some  current  action. 

Many  samples  were  collected  showing  the  marked 
difference  in  the  phosphate  content  between  these  alter- 
nating layers  and  in  a  specific  case  which  may  be  taken 
for  illustration,  a  sample  of  the  purest  phase  of  the  lime- 
stone in  a  given  ledge  yielded  less  than  1  per  cent,  cal- 
cium phosphate,  whereas  the  phosphate  lasers  inter- 
bedded  with  it  yielded  72.21  per  cent,  calcium  phosphate. 
That  is,  of  course,  an  extreme  difference  and  it  is  quite 
likely  that  all  the  transitional  compositions  may  be 
found  in  these  layers,  from  pure  limestone  at  the  one 
end  to  the  very  highest  grade  phosphate  at  the  other. 

In  the  bands  or  layers  which  are  notably  phosphatic, 
a  certain  minute  fossil — a  coiled  gastropod  of  the  genus 
cyclora — is  markedly  abundant.  In  some  specimens  the 
casts  of  the  interior  of  these  shells  are  so  numerous  as 
to  give  hand  specimens  an  oolitic  appearance.  Whether 
the  shells  of  these  small  organisms  were  originally 
phosphatic  cannot  be  stated  with  certainty.  The  fact 
that  the  exterior  shells  have  dissolved  and  left  only  casts 
of  the  interior  tends  to  indicate  that  the  exterior  shells 
were  calcareous.  Their  abundance  and  structure 
rendered  them  admirable  receptacles  for  the  finely  di- 
vided and  perhaps  almost  impalpable  calcium  phosphate 

47 


deposited  on  the  floor  of  the  Ordovician  sea  which  hard- 
ened in  the  shapes  of  the  interior  of  the  shells  in  which 
forms  they  are  now  found.  The  mechanical  role  which 
these  minute  organisms  played  in  the  concentration  of 
calcium  phosphate  was  apparently  a  very  important  one. 
Whether  the  chemical  role  was  of  any  importance  can- 
not be  stated,  nor  may  it  ever  be  known.  Clarke  and 
Wheeler's  results  do  not  indicate  that  the  gastropod 
tests  which  they  examined  are  important  carriers  of  cal- 
cium phosphate.  It  may  even  be  true  that  the  occurrence 
of  the  phosphate  at  certain  horizons  may  be  due  to 
mechanical  concentration  effected  by  the  abundance  of 
these  coiled  gastropods,  they  having  served  as  natural 
receptacles  for  it.  Large  organisms — the  brachiopods— 
likewise  acted  mechanically  as  receptacles  for  the  finely 
divided  phosphate  and  the  illustration  shows  the  cast  of 
the  interior  of  a  brachiopod — rafenisquina  alternata— 
collected  by  A.  M.  Miller  near  Versailles,  Woodford 
County,  Kentucky.  The  shell  itself  has  been  replaced  by 
silica,  a  portion  of  which  still  remains  as  the  white  patch 
in  the  illustration,  (Plate  XI.)  The  cast  of  the  interior 
has  been  formed  by  calcium  phosphate  which  forms  the 
mass  of  the  specimen. 

THE  METHOD  OF  CONCENTRATION. — The  evidence  re- 
veals that  a  great  deal  of  calcareous  material  was  de- 
posited with  the  phosphate  and  that  the  latter,  as  it  now 
occurs,  is  the  result  of  leaching  the  calcareous  parts  of 
the  originally  phosphatic  limestone.  Some  of  the  phos- 
phate as  now  observed  may  have  been  originally  quite 
rich  and  some  of  the  leaching  may  have  occurred  while 
the  deposits  were  yet  exposed  to  current  action  on  the 
ocean  floor.  This,  however,  is  pure  speculation.  It  is 
known  that  as  a  result  of  subaerial  leaching  the  dissem- 
inated phosphate  has  been  concentrated  as  the  calcar- 
eous parts  have  dissolved  away,  and  there  has  resulted 
a  fjur  grade  phosphate  deposit  from  what  was  a  low 
grade  material.  In  other  wonls,  the  brown  phosphate 
rock  deposit  of  Kentucky,  as  it  occurs  today,  rer^e^ents 
a  clear  case  of  secondary  concentration  or  enrichment. 

Several  factors  have  played  parts  in  the  leaching  or 
dissolving  of  the  calcium  carbonate  deposited  with  the 
phosphate.  It  is  presumed  that  the  solution  took  place 
by  conversion  of  the  normally  insoluble  lime  carbonate 

48 


to  the  soluble  bicarbonate  according  to  the  chemical  re- 
action. H2C03+CaC03=CaH2(C03)2.  The  carbon  diox- 
ide was  furnished  by  percolating-  meteoric  waters. 
Thus  the  first  factor  is  a  position  near  enough  to  the 
surface  to  be  brought  into  contact  with  surface  waters. 
In  describing  the  stratigraphy  of  the  phosphate  area, 
the  Brannon  member  was  stated  to  underlie  the  richest 
phosphate  horizon  in  central  Kentucky.  It  was  there 
described  as  a  firm,  hard  limestone,  a  good  water  bearer 
with  its  outcrop  marked  by  springs.  It  is  the  limestone 
occurring  in  the  numerous  sinks  of  this  region. 

The  overlying  member,  the  Woodburn,  which  carries 
the  phosphate  principally,  is  granular,  thin  bedded,  and 
likewise  contains  sinks.  In  other  words  it  is  of  a  char- 
acter to  readily  weather  and  dissolve  away.  This  com- 
bination of  an  underlying  more  or  less  impervious 
stratum  and  an  overlying  granular  limestone  is  an  ad- 
vantageous one  for  the  rapid  accumulation  of  phosphate 
and  no  doubt  was  an  important  factor  in  the  segregation 
of  the  phosphate  deposits.  Thus  the  character  of  the 
associated  sediments  may  be  considered  the  second  im- 
portant factor  in  the  rapidity  with  which  the  phosphate 
rock  may  concentrate. 

Two  other  factors  have  helped  the  leaching  process, 
namely,  the  laminated  character  of  the  limestones  and 
associated  phosphate  layers  already  referred  to,  ^ and 
the  joint  planes  which  are  characteristic  of  these  lime- 
stones, as  they  are  of  most  rocks.  The  leaching  of  the 
calcareous  portions  begins  along  the  joint  planes  between 
the  laminae,  especially  along  those  planes  between  the 
limestone  and  the  phosphate  bands,  which  afford  easy 
means  of  attack.  As  the  leaching  progresses  the  solu- 
tion cavities  along  the  joint  pianos  grow  wider  and 
deeper  and  ultimate  in  the  "cutters"  which  have  been 
already  described.  The  undissolved  masses  of  limestone 
remaining  between  the  cutters  are  called  " horses."  The 
cutters  have,  as  would  be  expected  from  the  theory 
ascribed  for  their  formation,  very  definite  courses— too 
great  a  regularity  to  admit  that  their  formation  has 
been  largely  fortuitous.  In  the  vicinity  of  Wallace  the 
courses  of  the  cutters  were  between  north  8°  west  and 
north  25°  west.  In  Mt.  Pleasant,  Tennessee,  where  much 
better  opportunities  exist  to  observe  this  phase  of  phos- 

49 


]>liate  occurrence,  the  trends  of  the  cutters  follow  quite 
definite  directions  also. 

The  limestones  not  only  are  leached  from  above  and 
on  the  sides  of  the  horses  (cutters),  but  solution  takes 
place  laterally,  or  along'  the  limestone  and  phosphate 
laminae,  so  that  actual  projecting  ledges  or  umbrella 
rr.eks  form  on  the  sides  of  the  horses.  Sometimes  leach- 
in  tv  proceeds  to  the  point  where  limestone  masses  actual- 
ly become  completely  detached  through  solution  and  lie 
amid  the  deposits  of  the  phosphate  rock. 

The  irregularities  of  the  underlying  rock  surface 
and  the  manner  in  which  the  phosphate  settles  down  on 
it,  has  given  rise  to  the  undulations  which  occur  in  the 
phosphate  rock  deposits.  These  phenomena  are  well 
bi  ought  out  in  the  illustrations.  The  intervening  clay 
layers  associated  with  the  phosphate  rock  represent  the 
original  beds  of  non-phosphatic  clay  bearing  limestone. 
This  material  weathers  to  a  product  commonly  referred 
to  as  muck. 

Disseminated  phosphate  sand  is  associated  with 
plate,  lump  or  hard  rock  and  with  the  muck.  Most  of 
this  disseminated  sand  without  doubt  represents  orig- 
inally disseminated  phosphate  rock  scattered  throughout 
the  (deposits  and  which  has  become  concentrated  through 
the  leaching  of  the  limestone.  Most  of  the  sand  is  sim- 
ply Cyclora  casts  composed  of  phosphate,  again  illustrat- 
ing the  important  mechanical  role  played  by  these  minute 
organisms  in  the  concentration  of  this  valuable  ferti- 
lizer. The  term  sand  is  not  a  good  one  from  the  view 
point  of  origin,  for  though  most  of  the  little  fragments 
are  rounded  as  fragments  of  such  casts  would  be  ex- 
pected to  be,  the  rounded  shapes  are  not  due  to  mechani- 
cal attrition,  but  are  original. 

Some  very  interesting  observations  on  Kentucky 
rock  have  been  made  by  Arthur  M.  Miller.*  Miller  be- 
lieves in  an  original  segregation  of  the  phosphate  de- 
posits, that  is,  a  segregation  at  the  time  they  formed  on 
the  ocean  floor.  He  says,  "this  original  segregation  of 
the  phosphate  has  in  no  case,  however,  given  deposits 
rich  enough  to  be  commercially  valuable.  The  latter  de- 
posits have  resulted  from  the  weathering  of  the  deposits 
of  the  first  concentration.  Though  concentrated  as  the 


>Ky.    Geol.    Survey,    Series  IV.,    Vol.    I.,    Pt.    I.,   1913,    pp.   327-328. 

50 


result  of  weathering,  we  do  not  believe  that  the  facts  of 
occurrence  warrant  the  explanation  that  in  weathering 
the  'carbonate  of  calcium  has  been  dissolved  out  leaving 
the  phosphate  of  lime  behind' — that  in  other  words  it 
is  simply  a  residual  deposit  due  to  the  leaching  out  of 
a  more  soluble  constituent. 

"Were  the  latter  the  case  it  should  be  possible 
to  find  many  instances  of  deposits  of  unleached  phos- 
phate where  the  amount  of  phosphate  in  the  same  volume 
of  deposit  equals  that  which  we  do  now  find  in  the 
weathered  commercial  deposits.  The  same  amount  of 
phosphate  should  be  there  plus  the  original  amount  of 
carbonate  of  lime1;  but  in  no  instance  is  this  the  case. 
On  the  contrary,  all  the  facts  point  to  an  actual  con- 
centration of  the  phosphate  into  less  volume  as  the  re- 
sult of  a  process  of  replacement.  "We  have  here  the 
same  phenomenon  as  is  illustrated  by  certain  iron  ore  de- 
posits. Water  with  iron  in  solution  is  checked  in  its 
downward  descent  by  meeting  relatively  impervious 
stratum.  Vnder  these  conditions  the  saturated  stratum 
(commonly  a  limestone)  immediately  above  the  relative- 
ly impervious  stratum  is  altered  by  replacement;  iron 
replaces  calcium,  the  latter  being  finally  carried  away  in 
the  form  of  bicarbonate  by  the  water. 

"So  in  the  case  of  concentrated  phosphate  of  lime 
deposits:  insoluble  tricalcium  phosphate  acted  upon  by 
organic  acids  in  the  superficial  layers  of  rock  waste  has 
its  phosphorus  rendered  soluble  ('available').  Entering 
into  solution  in  the  form  of  phosphoric  acid,  it  passes 
downward  to  the  lower  'rottenstone'  and  bed  rock  layers. 
Here  the  phosphorus  'reverts'  to  its  original  tricalcium 
phosphate  condition,  replacing  the  non-phosphatic  or 
relatively  non-phosphatic  limestone. 

"The  final  theoretical  reaction  is  expressed  by  the 
following  equation:  Ca.  H4  (POJ.,+2  Ca.  CO,=(PO4)2+ 
2H,O+2C(),." 

This  theory  of  the  formation  of  Kentucky  phosphate 
rests  on  the  solubility  of  calcium  phosphate.  Without 
any  doubt  this  compound  in  its  natural  state  is  sumcient- 
ly  soluble  to  bring  about  important  accumulations  over 
long  periods  of  time,  due  to  replacement,  and  possibly 
replacement  has  been  an  important  factor.  As  pointed 
out  above,  in  practically  unaltered  specimens  of  the  phos- 

51 


pliatic  layers  interbedded  with  limestone,  the  rich  phos- 
phatic  layers  are  present.  These  were  collected  by  the 
writer  and  analyses  made  in  the  survey  laboratories 
showed  more  than  70  per  cent,  in  calcium  phosphate. 
Foerste*  also  reports  mi  weathered  limestone  near  Ver- 
sailles from  the  Woodburn  member  carrying  55.5  per 
cent,  calcium  phosphate,  overlain  by  rock  containing 
only  9.39  per  cent,  of  the  same  ingredient.  Thus  to  the 
writer  the  idea  of  replacement  is  not  an  absolutely  nec- 
essary factor  in  accounting  for  the  concentration  of  the 
phosphate  rock.  He  is  willing  to  admit  that  replacement 
may  have  played  a  part,  but  feels  that  the  explanation 
that  has  been  given,  and  by  which  other  writers  have 
explained  the  formation  of  the  Tennessee  phosphate  de- 
posits, will  apply  to  the  Kentucky  field. 

THE  BROWN  PHOSPHATE  ROCK  INDUSTRY. 

GENERAL  CONDITIONS. 

The  Kentucky  phosphate  field  is  practically  a  virgin 
field.  From  its  study  and  a  comparison  of  it  with  the 
Tennessee  field,  the  writer  feels  that  local  conditions  are 
similar  and  the  problem  of  working  the  Kentucky  de- 
posits must  be  along  much  the  same  lines  as  in  Tennes- 
see. For  this  reason  it  is  thought  that  a  brief  descrip- 
tion of  the  mining  methods  employed  in  the  Mt.  Pleasant, 
Tennessee,  field  will  prove  of  interest  here. 

There  has  been  going  on  for  some  time  in  the  Mt. 
Pleasant  phosphate  field  and  without  doubt  in  other 
parts  of  the  Tennessee  brown  rock  phosphate  areas,  a 
change  that  will  result  in  leaving  very  little  or  no  wasted 
phosphate  rock  in  the  ground.  Some  phosphate  is  going 
into  the  waste  ponds,  but  the  time  will  without  doubt 
come  when  all  this  material  will  be  reworked,  and  even 
now  some  companies  are  working  or  planning  to  work 
these  old  tailings.  Modern  mining  and  milling  methods 
of  the  last  decade  have  revolutionized  the  brown  rock 
phosphate  industry,  and  incidentally  are  conserving  this 
valuable  fertilizer  material.  They  are  in  striking  con- 
trast with  the  crude  and  wasteful  methods  formerly  em- 
ployed. When  phosphate  was  first  mined  in  Tennessee 
it  is  safe  to  say  that  at  least  half  of  the  good  material 
such,  for  example,  as  is  now  being  worked  was  thrown 

*Loc.  Cit.,   p.  381. 

52 


away.  A  great  deal  of  this  cannot  in  the  nature  of  things 
be  recovered,  for  in  the  course  of  time  it  has  become 
so  thoroughly  mixed  with  clay  and  in  places  so  covered 
with  overburden  as  to  make  its  recovery  at  a  profit  im- 
possible. The  lessons  learned  in  Tennessee  no  doubt  will 
be  of  value  in  working  the  brown  phosphate  deposits  in 
central  Kentucky. 

The  object,  of  course,  in  preparing  phosphate  for 
market  is  to  remove  as  much  of  the  clay,  chert,  and 
limestone  as  possible  from  it.  It  is  not  possible  to  re- 
move all  these  impurities,  especially  in  the  case  of  clay 
and  sand.  There  is  no  sharp  division  between  the  finest 
phosphate  sand  and  clay  and  it  would  obviously  be 
wasteful  to  carry  the  process  of  obtaining  fine  phosphate 
sand  beyond  the  point  where  the  cost  would  offset  the 
value  of  the  phosphate  obtained.  This  is  one  of  the  prac- 
tical considerations  connected  with  the  modern  conserva- 
tion of  phosphate  rock  which  perhaps  has  not  always 
been  given  just  and  deserved  consideration.  These  prac- 
tical difficulties  have  resulted  in  the  loss  of  much  fine  phos- 
phate along  with  the  silica  sand  and  clay.  Owing  to  the 
similarity  of  finely  divided  phosphate  and  silica  sand  in 
specific  gravity,  no  mechanical  process  has  been  de- 
veloped to  effect  a  further  saving.  As  the  problem  now 
stands  the  general  development  of  some  concentration 
process  is  required  to  effect  a  further  recovery  of  low 
grade  phosphate  both  in  Tennessee  and  Florida,  where 
the  consumers  are  demanding  a  high  grade  product. 

The  point  beyond  which  it  is  not  practicable  to  carry 
preparatory  treatment  is  not  fixed  and  standards  vary 
from  time  to  time  and  probably  at  a  given  time  among 
individuals  or  corporations.  Thus  in  the  phosphate  min- 
ing industry  as  practiced  in  Tennessee  in  the  early  nine- 
ties, rock  was  discarded  which  has  a  high  value  today, 
and  the  former  apparent  lapses  from  the  highest  stand- 
ards have  in  the  course  of  time  proven  to  be  not  lapses  at 
all,  but  simply  necessities  imposed  by  trade  conditions 
of  the  time.  In  other  words  the  phosphate  once  discard- 
ed is  now  being  used.  The  open  cut  or  surface  methods 
of  mining  brown  rock  as  practiced  in  the  Tennessee  field, 
and  which  will  be  the  methods  employed  in  the  Ken- 
tucky field,  are  peculiar  in  this  respect  and  the  gen- 


53 


eralizatious  made  do  not  cover  many  other  classes  of 
mining-  and  certainly  will  not  apply  to  underground  min- 
ing- in  general. 

GRADES  OF  COMMEIKTAL  IJKOWX  PHOSPHATE  ROCK. 

Most  of  the  brown  phosphate  rock  from  the  Mt. 
Pleasant,  Tennessee,  field  is  shipped  in  three  grades, 
namely,  those  containing  72,  75,  and  78  per  cent,  of  cal- 
cium phosphate.  The  percentage  of  iron  and  aluminum 
oxides  ("I  and  A")  remaining  in  the  washed  product 
has  an  important  hearing  on  the  value  of  the  rock.  The 
usual  guarantees  are  given  below.  .For  each  per  cent, 
in  excess  of  the  guaranty,  '2  per  cent,  of  calcium  phos- 
phate. (BPL)  is  deducted'. 

Table    of    Guarantees    C-howir.g    the    Relation    Between  Phosphate:    and 
ii  on   rnci    Alurrunn    CcnLeni. 

Fe_O.;+Al,O:; 

BPL  T  and  A 

Per  cent.  Per  cent. 

70  6.5 

72  5.5 

75  5.0 

76  4.1 
78  to   80  4.0 

Five  to  five  and  a  half  per  cent,  iron  oxide  and 
alumina  is  the  usual  maximum  allowed  and  that  is  usual- 
ly referred  to  as  "I  and  A"  in  the  trade  and  in  com- 
mercial analyses.  At  one  time  only  rock  of  78  per  cent. 
grade  was  shipped  from  the  Mt.  Pleasant  field  and  rock 
of  this  grade  is  still  known  as  ' ( export  rock. ' '  The  guar- 
anteed content  in  phosphate  of  lime,  "bone  phosphate" 
or  "BPL"  as  it  is  commonly  referred  to  in  the  trade, 
next  fell  to  75  per  cent.,  and  at  the  present  time  many 
of  the  companies  are  finding  it  difficult  to  ship  this  grade 
exclusively,  and  the  life  of  the  75  per  cent,  rock  is  limited. 
Every  per  cent,  of  iron  oxide  and  alumina  less  than  the 
5  per  cent.,  is  regarded  as  equivalent  to  an  additional  2 
per  cent,  of  calcium  phosphate,  for  it  is  considered  that 
in  the  subsequent  treatment  of  the  phosphate  in  the  man- 
ufacture of  fertilizers  the  harmful  effect  of  1  per  cent, 
of  iron  oxide  and  alumina  offsets  the  good  effect  of  2 
per  cent,  of  calcium  phosphate.  If  much  more  than  5  per 

54 


cent,  of  iron  oxide  and  alumina  are  present  the  superphos- 
phate tends  to  become  gummy  and  farmers  find  it  difficult 
to  drill  it  into  the  land. 

A  few  samples  of  Kentucky  phosphate  rock  were  se- 
lected for  analysis  for  their  content  in  iron,  alumina, 
and  fluorine,  in  addition  to  their  content  in  phosphate  of 
lime.  The  results  of  these  analyses  are  given  below.  The 
content  in  iron  and  alumina  shown  are  too  high  to  come 
within  the  normal  commercial  requirements  of  the  pres- 
ent time  and  indicate,  as  pointed  out  in  other  places  in 
this  paper,  that  the  bulk  of  the  Kentucky  phosphate  rock 
will  no  doubt  have  to  wait  for  the  general  introduction  of 
cheap  chemical  or  other  processes  of  concentration  be- 
fore it  is  able  to  compete  with  the  high  grade  phosphate 
rock  from  the  other  eastern  states. 

Analyses   of    Kentucky    Phosphate  Rock. 

(W.  C.  Wheeler  and  R.  M.  Kamm,  Analysts.) 

Ca3(PO4),  ALO3  Fe,O:;  F. 

No.  108B                              63.87  5.29  2.09  1.38 

No.  112A                              60.87  4.35  3.50  1.02 

No.  120                                  28.92  7.46  5.29  0.70 

No.  126B                              54.25  4.63  1.42  1.18 

No.  133                                 24.56  10.66  6.62  0.85 

No.  141                                  35.21  5.21  5.29  0.92 

No.  143                                  37.56  2.50  6.05  0.95 

No.  108B.  Mrs.  M.  Murray  farm,  1%  miles  southeast  of  Wallace, 
and  north  of  Frankfort  and  Lexington  pike. 

No.  112A.  Henry  L.  Martin  estate,  %  mile  east  of  Wallace,  and 
north  of  Frankfort-Lexington  pike. 

No.  120.     H.  L.  Martin,  Jr.  estate,  l1/^  miles  southeast  of  Midway. 

No.  126B.  James  J.  Nugent,  in  orchard  just  northeast  of  Wallace 
crossroads. 

No.  133.  E.  L.  Lillard  estate,  2ys  miles  southeast  of  Midway,  near 
South  Elkhorn  Creek. 

No.  141.  E.  L.  Davis  estate,  along  the  Louisville  and  Nashville 
Railroad  in  small  sink,  1%  miles  northwest  of  Midway. 

No.  143.  Mrs.  Charles  Nuckols  estate,  1%  miles  northwest  of 
Midway. 

PREPARATION  OF  PHOSPHATE  ROCK  FOR  MARKET. 

There  are  many  stages  to  be  considered  under  the 
head  of  preparation  of  phosphate  rock  for  market,  but 
they  may  all  be  subdivided  into  3  major  operations  as 

55 


follows:  (1)  removal  of  overburden;  (2)  mining;  and 
(3)  milling,  in  which  is  included  drying.  The  present 
methods  of  utilizing  and  thus  preserving  from  loss  the 
brown  phosphate  rock  supplies,  especially  in  the  Mt. 
Pleasant  field,  are  included  under  the  above  headings 
and  therefore  will  be  described  in  connection  with  them 
insofar  as  this  can  be  done. 

REMOVAL  OP  OVERBURDEN. 

The  overburden  of  the  brown  rock  phosphate  de- 
posits in  the  Mt.  Pleasant,  Tennessee,  field  varies  from 
one  foot  upwards.  Usually  it  is  less  than  20  feet,  but  a 
thickness  of  30  feet  is  known  but  is  excessive  in  those 
places  where  mining  has  been  in  progress.  The  methods 
of  removal  of  overburden  are  diverse.  Under  exceptional 
conditions  the  old  time  crude  and  expensive  hand 
methods  have  to  be  resorted  to,  but  in  most  places,  es- 
pecially where  virgin  ground  is  being  opened  up  and 
where  conditions  are  comparable  with  what  may  be 
expected  in  Kentucky,  operations  are  conducted  in  the 
most  up-to-date  fashion,  as  the  illustrations  (Plates 
XII.  to  XVI.)  show.  Where  the  overburden  is  not  very 
thick  or  hard  it  may  be  simply  pried  up  and  removed 
with  scrapers  (Plate  XII. ),  or  it  may  be  loosened  with 
dynamite  and  then  removed  with  scrapers.  A  favorite 
method  of  getting  rid  of  the  overburden,  used  especially 
in  ground  that  is  being  reworked,  is  to  first  "hog"  or 
undercut  it,  pry  it  off  with  bars,  and  then  scrape  or 
carry  it  away.  The  drag  line  excavator  (Plate  XIV.) 
and  the  steam  shovel  (Plate  XV.)  are  types  of  up-to- 
date  machinery  used  to  remove  overburden  in  the  Ten- 
nessee field.  The  hydraulic  method  (Plate  XVI.)  is 
also  used  and  this  would  do  well  in  the  vicinity  of  Elk- 
horn  Creek,  Kentucky.  Both  the  overburden  and  the 
rock  beds  are  removed  by  this  last  named  method,  which 
is  simplicity  itself  in  action  and  which  requires  a  mini- 
mum of  labor  in  operation,  namely  one  man  to  handle 
the  hydraulic  gun  and  two  to  keep  the  sluices  clear.  Of 
course  this  last  named  method  can  only  be  used  where 
there  is  an  abundant  water  supply. 

Occasionally  narrow  benches  are  stripped  by  hand 
methods.  The  dirt  is  more  or  less  undermined  by  the  re- 
moval of  the  underlying  rock  and  the  bank  caved  over 

56 


into  the  previously  mined  outbench  by  prying  with  under 
rods  from  above.  In  the  case  of  deposits  stripped  by 
scraper  outfits,  (Plate  XII.)  the  outfits  are  such  as  are 
used  in  ordinary  railroad  work  and  consist  usually  of 
ordinary  and  five  wheeled  scrapers  with  a  hook  team 
extra  and  a  plow  team.  This  work  is  usually  contracted 
at  141/2  cents  per  cubic  yard.  The  major  portion  of  the 
stripping  is  now  done  by  class  14  Bucyrus  Drag  Line 
Excavators  mounting  a  70-foot  boom  with  a  iy2  yard 
bucket.  (Plate  XIV.)  This  machine  is  adapted  to  the 
removal  of  overburden  that  does  not  average  more  than 
15  feet  in  thickness.  With  more  than  this  depth  the  pits 
become  too  narrow  at  the  bottom. 

In  Hickman  County,  Tennessee,  where  the  over- 
burden averages  30  feet,  a  class  24  drag  line  machine 
has  been  used.  This  has  a  100-foot  boom  and  a  3V>  yard 
bucket. 

In  general  it  cannot  be  said  that  the  workability  of 
a  bed  is  regulated  by  the  depth  of  overburden.  There  are 
other  factors  entering  into  the  problem.  If  the  phos- 
phate bed  is  a  very  thick  one,  the  overburden  may  be 
quite  thick  and  still  may  be  removed  and  the  operation 
be  a  profitable  one.  On  the  other  hand,  if  the  bed  is 
very  thin  but  exceedingly  high  grade,  it  may  still  pay 
to  remove  what  appears  to  be  an  excessively  thick  over- 
burden. 

COSTS  OF  REMOVAL  OF  OVERBURDEN. 
The  cost  of  operating  the  class  14  machines  is  as 
follows : 

Cost  of  Operating  Class  14  Bucyrus  Drag  Line  Excavator. 

Per  Shirt. 

1  runner  ($150  per  month)  $6.00 

1  fireman  2.50 

1  teamster  1.75 

1  ground  man 1.50 

1  foreman  3.00 

1  team  (owned  by  company)   3.00 

Coal,  2  tons  at  $2.40 4.80 

Cable  wear 5.00 

Repairs,  oil,  and  supplies  3.00 

6%  interest  on  $13,000;   250  shifts  3.20 

10%   depreciation  ..  5.20 


$38.95 
57 


The  above  items  of  expense  are  for  a  machine  hav- 
ing caterpillar  traction  for  moving.  If  a  timber  and 
roller  machine  is  used  an  extra  ground  man  is  required. 
The  capacity  averages  1,000  cubic  yards  per  10-hour 
shift,  though  often  .1,300  to  1,400  yards  are  dug  under 
favorable  conditions.  While  the  larger  size  machines 
average  more  in  yardage,  the  operating  costs  also  in- 
crease so  that  the  cost  per  yard  is  nearly  the  same. 

In  those  mines  where  hydraulic  stripping  is  used 
owing  to  the  excessive  depth  of  overburden,  or  where 
mining  conditions  require  it,  the  cost  of  removal  amounts 
to  about  7  cents  per  cubic  yard.  At  two  mines  in  Tennes- 
see where  this  method  is  employed  the  bank  is  cut  down 
by  a  hydraulic  monitor,  using  a  2  o.r  2~\t>  inch  tip.  The 
water  pressure  usually  needed  is  150  to  175  pounds  per 
square  inch.  The  water  flows  back  from  the  face  carry- 
ing from  10  to  20  per  cent,  solids  into  a  pump  well.. 
From  the  sum})  the  Avater  and  overburden  are  pumped 
to  the  waste  ponds  by  an  8-inch  direct  connected  motor 
driven  centrifugal  pump.  The  pump  requires  from  1,500 
to  2,000  gallons  of  water  per  minute  for  full  capacity 
with  a  75  horse  power  motor. 

METHODS  OF  MINING. 

Much  of  the  mining  in  the  Mt.  Pleasant,  Tennessee, 
field  has  been  done  by  hand  on  account  of  the  method 
of  occurrence  of  the  brown  rock.  The  steam  shovel  has 
not  proved  successful  because  it  is  unable  to  discrim- 
inate between  the  grades  of  ore  mined,  with  the  result 
that  much  clay  and  flint  get  into  the  product  and  has 
to  be  removed  subsequently.  The  cantilever  adjunct  to 
mining  which  is  employed  at  one  mine  in  the  Mt.  Pleas- 
ant, Tennessee,  field  is  unique.  The  hydraulic  method  of 
mining  is  used  at  two  plants  and  has  many  advantages 
as  pointed  out  under  the  preceding  topic.  These  me- 
chanical, methods  of  mining  and  removing  overburden 
which  have  cheapened  operating  costs,  have  played  the 
major  part  in  conserving  Tennessee  brown  phosphate 
rock  and  without  doubt  will  be  the  means  whereby  Ken- 
tucky rock  may  hope  to  take  its  place  on  the  market. 

As  hydraulicking  is  practiced  in  Tennessee,  the 
limestone  horses  often  get  in  the  way  and  have  to  be 
blasted  out.  But  this  is  not  difficult,  owing  to  the  loose 
or  platy  character  of  the  phosphatic  limestone  associated 

58 


with  the  brown  rock  deposits.  In  addition  to  the  hy- 
draulic method  which  may  be  employed  only  in  certain 
favorable  locations,  hand  mining  is  also  employed,  es- 
pecially where  the  ground  is  being  reworked.  Where 
hand  mining  is  practiced  the  ore  is  usually  screened  on 
the  spot  where  the  miner  is  at  work.  The  fine  material 
passes  through  the  screen  and  is  saved  and  washed,  and 
the  coarse  rock  which  is  left  is  hauled  away  and  dried 
by  burning  on  ricks  of  wood  in  the  open  (see  Plate  XVII), 
thus  saving  rehandling  in  the  mill.  The  lump  rock,  as 
mined,  usually  contains  from  20  to  21  per  cent  of 
moisture  and  drying  it  in  this  way  reduces  the  moisture 
to  1  per  cent,  or  less.  In  certain  places  where  mining  with 
the  hydraulic  giant  is  not  practicable  or  where  the  giant 
fails  to  get  all  the  rock,  hand  mining  has  to  be  resorted 
to. 

WORKING  CUTTERS. 

The  term  "cutters"  has  been  explained  and  the  fact 
that  the  phosphate  rock  in  them  was  left  unmined  in  the 
early  days  of  brown  rock  mining  has  been  pointed  out. 
The  development  of  cutters,  which  took  place  along  orig- 
inal joint  plains,  varies  greatly  within  the  restricted  Mt. 
Pleasant  field  and  may  be  expected  to  vary  much  in  the 
Kentucky  field.  In  some  places  in  Tennessee  they  are  of 
large  size  and  some  were  observed  30  to  35  feet  wide 
and  as  much  as  20  to  25  feet  deep  (Plate  XVIII.),  averag- 
ing probably  18  to  20  feet.  In  these  abnormally  wide 
and  deep  cutters,  it  is  not  uncommon  to  have  small  lime- 
stone horses.  Some  of  the  cutters,  on  the  other  hand, 
are  so  narrow  that  the  phosphate  rock  in  them  can  be 
removed  only  with  difficulty.  (Plate  XIX.) 

Hand  methods  of  mining  have  to  be  employed  almost 
exclusively  to  remove  phosphate  rock  from  these  cutters 
owing  to  the  peculiar  method  of  its  occurrence.  (Plates 
XVIII.  and  XIX.)  Hydraulic  methods  have  been  employ- 
ed in  places.  Owing  to  the  depth  of  the  cutters  the  work 
has  been  done  in  benches  of  convenient  height  for  the 
miners,  (Plate  XVIII.)  The  ore  is  picked  out  and  shoveled 
from  bench  to  bench  and  finally  into  wagons,  in  which  it 
is  hauled  to  the  mills.  Mining  the  deep  cutters  is  usually 
carried  on  in  fair  weather  and  when  the  roads  are  good. 
In  working  over  virgin  ground  at  the  present  time  the 
rock  in  the  cutters  is  readily  and  cheaply  obtained  by 

59 


the  cantilever  method.  (Plate  XIII.)  The  material  from 
the  shallow  cutters  is  picked  out  and  screened  on  the 
tines  of  a  phosphate  fork  or  on  a  small,  movable,  1-inch 
mesh  screen.  The  coarse  rock  is  dried  or  burned  on 
ricks  of  wood  (Plate  XVII.),  and  the  muck  is  taken  to  the 
mill  where  it  is  washed.  The  old  cutters  containing  phos- 
phate rock  are  located  by  hand  prospecting  with  a  long- 
sharp  steel  rod. 

THE  COST  OF  MINING  PHOSPHATE  ROCK. 

The  cost  of  mining  phosphate  rock  depends  on  sev- 
eral factors,  chief  among  which  is  the  depth  and  expense 
connected  with  the  removal  of  the  overburden.  It  will 
be  of  interest  to  note  here  average  costs  in  the  most  im- 
portant phosphate  producing  states.  In  South  Carolina 
during  the  past  ten  years,  as  much  as  22  feet  of  over- 
burden have  been  profitably  removed  and  river  rock  has 
been  dredged  from  a  depth  of  52  feet,  including  a  cover 
of  16  feet  of  sand  and  muck.  In  Florida,  where  a  higher 
grade  rock  is  produced,  it  is  profitable  to  mine  rock  hav- 
ing an  overburden  of  greater  depth  than  20  feet — the 
average  maximum  in  South  Carolina.  According  to  data 
furnished  by  various  companies  to  the  Federal  Trade 
Commission*  the  cost  of  mining  Florida  land  pebble,  in- 
cluding washing,  drying,  etc.,  ranges  from  about  $1.65 
to  $2.50  per  gross  ton,  not  including  amortization  of  in- 
vestment or  royalties  in  case  the  mining  is  done  on  that 
basis.  The  cost  of  mining  Tennessee  brown  rock  ranges 
from  about  $2.75  to  $3.14  per  gross  ton  and  these  are 
the  figures  of  greatest  interest  in  connection  with  the 
Kentucky  field.  The  cost  of  mining  rock  in  South  Caro- 
lina is  considerably  higher.  The  following  figures  were 
taken  from  the  average  costs  of  a  Tennessee  mine  during 

six  months  of  good  mining  weather  :f 

Per  ton  cents. 

Mining  $0.64 

Transportation  and  team  expense 0.23 

Washing    0.46 

Drying   0.47 

Shipping  and  track  expense  0.09 


Total  per  long  ton  of  dry  rock  $1.89 


*Rept.   on  the  fertilizer  industry,   1916,   p.   101. 

fBarr,    James  A.     Tenn.   Phosphate  Products.     Bull.    No.   93,    Am.   Inst. 
Min.   Engrs.,    Sept.,  1914,   p.   2410. 

60 


The  work  of  mining-  is  chiefly  done  by  contract,  the 
price  being  25  cents  per  tram  when  one  handling  only 
is  required.  Where  two  casts  are  required  35  to  40  cents 
per  tram  is  paid.  The  miners  keep  the  track  up  to  the 
mining  face. 

WASHING  AND  DRYING. 

The  washing  processes  whereby  the  mined  brown 
phosphate  rock  is  treed  from  clay,  chert,  and  limestone 
are  elaborate  and  the  mills  in  which  the  work  is  done  are 
for  the  most  part  large  and  modern.  These  modern  wash- 
ing plants  which  have  done  so  much  to  make  the  mining 
of  low  grade  brown  rock  profitable,  and  which,  therefore, 
are  playing  such  an  important  role  in  the  conservation 
of  this  class  of  phosphate  rock,  have  practically  all  been 
installed  during  the  past  10  or  15  years.  The  principles 
of  the  washing  process  are  identical  throughout  but  the 
details  of  manipulation  differ  at  different  plants.  The 
phosphate  rock  as  mined  is  brought  to  the  washer  either 
in  wagons  or  by  tram.  Where  hydraulic  mining  is  prac- 
ticed it  goes  to  the  plant  through  a  flume.  The  material 
mixed  with  water  is  delivered  into  a  hopper  at  the  top 
of  the  mill  and  the  subsequent  operations  for  the  most 
part  are  conducted  by  gravity.  From  the  hopper  the  rock 
passes  through  a  toothed  revolving  crusher  and  then 
into  log  washers.  From  the  washers  it  passes  to  a 
cylindrical  or  conical  screen  with  circular  perforations. 
The  coarse  or  lump  rock  which  fails  to  pass  through  the 
screen  passes  on  to  a  picking  belt  where  limestone  and 
chert  fragments  and  clay  balls  are  removed.  The  ma- 
terial then  goes  to  the  wet  storage  sheds  or  piles  to  be 
later  dried.  The  fine  material  may  go  through  a  settler 
or  clarifier  provided  with  riffles,  or  through  several  set- 
tling tanks  in  succession  in  which  the  sand  settles  out. 
The  clay  and  sand  not  caught  in  the  process  goes  to  the 
waste  ponds.  The  above  description  briefly  outlines  the 
fundamentals  of  the  washing  process  as  carried  out  at 
most  of  the' plants  handling  brown  rock  phosphate  in  the 
Mt.  Pleasant,  Tennessee,  field,  but,  of  course,  as  has  been 
mentioned,  details  are  widely  divergent. 

The  clay  and  the  phosphate  sand  which  pass  to 
the  waste  ponds  are  of  great  interest  in  the  problem  of 
conservation.  When  the  material  reaches  the  waste  pond 

61 


the  coarse  sand  settles  out  first  and  naturally  nearest 
the_  end  of  the  waste  pipe  or  flume.  This  material  is  the 
highest  in  calcium  prosphate.  It  is  planned  to  work  ma- 
terial of  this  character  at  one  of  the  plants  near  Mt. 
Pleasant,  and  already  at  another  the  old  tailing  dumps 
are  being  worked.  At  this  plant  much  attention  has  been 
paid  to  the  process  of  separating  the  clay  and  phosphate 
sand.  There  is  a  washer  at  this  particlar  plant  which 
differs  from  any  other  in  this  field  and  is  most  throuogh 
in  its  action.  The  clay  resulting  from  the  action  of  this 
washer  was  observed  in  the  waste  pond.  It  has  been  in 
suspension  for  a  long  time  and  material  taken  and 
nibbed  between  the  fingers  appeared  of  almost  impalpa- 
ble fineness.  Some  of  the  phosphate  sand  from  this  wash- 
ing process  is  so  fine  in  texture  that  it  sifts  through 
the  meshes  of  the  sacks  in  which  it  is  shipped.  It  has 
been  suggested  that  material  from  such  waste1  ponds 
might  be  used  in  its  present  form  on  farm  lands,  but  this 
lias  been  found  impracticable  as  it  will  not  bear  the  cost 
of  transportation,  but  the  high  phosphate  content  in  cer- 
tain of  the  samples  collected  from  such  waste  ponds  is 
noteworthy. 

Drying  is  accomplished  in  two  very  different  ways 
which  arc  representative  of  the  old  and  new  methods 
employed  in  the  Tennessee  brown  phosphate1  field.  At 
nearly  all  the  large  plants  modern  rotating'  cylindrical 
dryers,  similar  to  rotary  cement  kilns,  are  in  use,  but 
the  rock  is  fed  both  at  the  hot  and  cold  ends.  It  would 
seem  that  the  latter  method  would  be  the  more  efficient. 
There  is  generally  some  special  cause  when  the  old 
fashioned  method  of  drying1  on  wood  ricks  is  employed 
and  where  it  is  in  use  it  generally  saves  extra  additional 
handling  or  haulage.  Drying*  generally  reduces  the 
moisture  present  from  20  or  21  per  cent  to  1  or  2  per 
cent. 

CONSERVATION  OF  FINES. 

In  drying1  phosphate  rock  large  quantities  of  ma- 
teiial  in  finely  divided  form  is  lost  by  being  carried  out 
of  the  fiue,  owing  to  the  powerful  drafts  employed,  es- 
pecially in  the  modern  types  of  dryers.  At  many  of  the 
plants  steps  have  been  taken  to  save  this  material.  This 
is  accomplished  by  means  of  bends  in  the  flue,  or  by 

62 


hoods  or  baffles.  The  analysis  of  the  fine  material  caught 
and  saved  at  some  of  the  plants  indicates  that  it  is  well 
worth  saving. 

THE  PHOSPHATE  INDTSTKV  AT  WALLACE, 
KENTUCKY. 

The  phosphate  deposits  on  certain  farms  near 
Wallace  at  the  time  of  the  writer's  visit  were  under  lease 
by  the  Central  Kentucky  Phosphate  Company.  Since 
then  (June,  1915)  they  have  changed  hands  and  are  now 
being  worked  by  the  United  Phosphate1  and  Chemical 
Company  which,  it  is  understood,  is  a  subsidiary  of  the 
Charleston,  South  Carolina,  Mining  and  Manufacturing 
Company.  Since  work  started  at  Wallace  some  few  years 
ago  it  has  been  carried  on  intermittently  and  there  have 
been  many  shut  downs  lasting  for  short  or  long  periods. 
The  total  tonnage  removed  from  the  Wallace  workings 
has  been  small  and  in  all  has  not  amounted  to  more  than 
a  few  thousand  tons  (1,500  to  2,000  tons).  Since  the  writer 
visited  the  plant  in  June,  1915,  it  has  been  added  to  con- 
siderably, and  it  is  expected  to  resume  operations  on  a 
larger  scale  than  ever  early  in  1917.  In  the  early  part 
of  this  year,  the  Hawkins  farm,  which  adjoins  that  on 
which  the  old  workings  are  located,  has  been  acquired 
and  it  is  planned  to  work  out  to  the  Steele  and  Murray 
farms  which  are  nearby  and  under  lease. 

The  overburden  at  the  Wallace  workings  varies 
from  a  fraction  of  a  foot  to  5  or  6  feet  in  thickness.  It 
occasionally  reaches  10  feet.  Due  to  its  thinness,  it  may 
be  removed  directly  by  scrapers,  after  it  is  first  plowed 
up  or  loosened  with  pick  and  shovel. 

After  the  removel  of  the  overburden,  the  phosphate 
rock  is  usually  removed  with  pick  and  shovel,  loaded  by 
hand  en  to  wagons,  and  hauled  to  the  mill.  The  deposit 
at  Wallace  normally  ranges  from  3  to  5  feet  in  thickness. 
The  extremes  of  thickness  are  1  foot  and  10  feet.  When 
the  ore  is  of  the  maximum  thickness  it  proved  too  costly 
to  remove  it  all  according  to  the  methods  employed  in 
this  field. 

Electric  power  is  used  at  the  mill.  The  ore  at  the 
mill  is  shoveled  on  to  a  belt  which  feeds  it  to  a  revolving 
cylindrical  dryer  40  feet  long  and  5  feet  in  diameter. 
This  is  fed  with  coal  which  is  burned  under  a  forced 

63 


draft.  The  ore  in  the  dryer  travels  forward  and  down- 
ward to  the  hotter  end.  From  the  dryer  it  falls  into  a 
pit  through  which  passes  an  endless  bucket  conveyor, 
which  carries  it  to  .a  horizontal  screen  conveyor.  The 
latter  in  turn  transfers  it  to  a  hopper  through  which  it 
falls  on  to  burrs  or  grinders.  Before  falling  on  to  the 
burrs,  the  lump  rock  is  screened,  only  those  fragments 
which  are  %  inch  or  less  in  diameter  going  into  the 
crushers.  The  screen  is  a  cylindrical  affair  containing 
V-2  inch  holes.  All  the  lump  rock  passes  over  the  screen 
to  a  conveyor  and  goes  to  a  loading  bin  to  be  wheeled  on 
to  cars  later,  or  it  may  be  clmted  directly  on  to  cars. 

The  material  which  has  passed  through  the  crushers 
is  further  ground  to  phosphate  flour  and  conveyed  by 
elevators  to  its  own  bin.  The  ground  rock  is  bagged  in 
paper  bags  of  100  or  200  pounds  each,  and  shipped  in 
this  form  for  direct  application  to  the  soil. 

The  old  company  whose  methods  are  described  above 
has  a  spur  built  to  its  plant  from  a  short  branch  line  of 
the  Southern  Railway  running  between  Georgetown  and 
Versailles,  Kentucky.  The  new  company  proposes  to 
grade  tracks  to  those  farms  it  proposes  to  work. 

TRANSPORTATION  FACILITIES. 

The  Wallace  area  and  the  area  to  the  west  of  Mid- 
way are  admirably  located  with  respect  to  railroad  trans- 
portation. The  main  line  of  the  Louisville  and  Nashville 
Railway  between  Lexington  and  Louisville,  passes 
through  Midway  and  the  phosphate  area  to  the  west  be- 
tween Midway  and  Spring  Station.  A  branch  of  the 
Southern  Railway  between  Versailles  and  Georgetown 
passes  through  the  heart  of  the  Wallace  area,  and  the 
topography  or  lay  of  the  land  about  Wallace  is  such  that 
spur  tracks  may  be  built  where  needed  at  a  minimum  of 
expense.  The  railroad  requirements,  therefore,  could 
hardly  be  improved  upon. 

The  Kentucky  deposits  are  also  well  located  from 
the  viewpoint  of  distribution  to  the  north  in  Ohio,  and 
northwest  in  Indiana  and  Illinois,  where  more  and  more 
raw  ground  rock  is  coming  into  use.  The  freight  rates 
from  Midway  to  Louisville,  Cincinnati,  and  Cleveland 
are  in  each  case  less  than  from  Mt.  Pleasant,  Wales  Sta- 
tion, and  Nashville,  Tennessee,  and  this  difference  in 

64 


freight  rates  may  compensate  for  a  lesser  content  in 
calcium  phosphate  in  the  Kentucky  rock,  and  where  com- 
position and  other  conditions  are  equal,  result  in  a  de- 
mand for  the  latter. 

The  following  table  is  of  interest  in  this  connection: 

Freight   Rates   From    Mines   in    Kentucky  and   Tennessee  to   Important 
Near  By   Markets. 


Destination.  Location   of  Mines.  Freight  Rates. 


[Midway,    Ky.    .. $1.60 

Cincinnati,  Ohio Mount  Peasant,  Tenn.  ..  2.50 

Wales  Station,  Tenn.   ..                           2.50 

[Nashville,  Tenn 1.80 

fMidway,   Ky 1.60 

Louisville,  Ky....  .  J  Mount   Pleasant>    Tenn 2.25 

A  Wales   Station,  Tenn 2.25 

Nashville,    Tenn.  1.55 

\_ 

fMidway,   Ky 3.22 

I  Mount  Pleasant,  Tenn 3.80 

Cleveland,  Ohio J  TTT  . 

Wales   Station,  Tenn 3.80 

Nashville,  Tenn.  .  3.12 


RAW  ROCK  PHOSPHATE. 

Finely  ground  rock  phosphate,  sometimes  called 
"floats,"  is  used  to  a  considerable  extent  by  farmers, 
particularly  in  the  middle  west,  as  a  source  of  phos- 
phorus. It  is  often  lower  in  phosphate  of  lime  and  con- 
sequently higher  in  iron  and  alumina  than  rock  used 
for  acidulating  purposes.  In  the  raw  condition,  the  iron 
and  alumina,  if  in  the  form  of  phosphate,  are  advan- 
tageous according  to  certain  scientists  who  have  ex- 
perimented with  these  phosphates,  because  they  have  been 
found  to  supply  a  favorable  medium  for  the  germination 
of  seeds.  Floats  are  applied  directly  in  turning  under 
crops,  or  are  mixed  with  barnyard  manure  on  the  theory 
that  the  phosphoric  acid  is  liberated  and  rendered  avail- 
able by  the  action  of  the  weak  organic  acids  generated 
during  the  decomposition  of  the  manure. 

The  future  of  the  Kentucky  phosphate  field  as  a 
source  of  raw  ground  rock  ought  to  be  good.  The  use 

65 


of  this  material  in  the  states  to  the  north  and  west  is 
becoming  increasingly  popular.  The  advantages  in 
freight  i  ates  as  compared  with  the  nearest  competing 
field  in  similar  rock,  the  quality  and  other  factors  being 
equal,  is  important,  as  is  also  the  additional  fact  that 
a  high  content  in  iron  and  alumina  in  the  raw  rock  is 
not  considered  sncli  a  drawback  as  in  rock  which  is 
acidulated  in  making  acid  phosphate  for  mixed  fertil- 
izers. Floats  have  been  shipped  in  the  past  from  the 
Kentucky  field  when  operations  have  been  in  progress 
in  that  locality. 

PIIOSPHATir  LIMESTONE  AS  A  SOTKCE  OF 
PHOSPHATE. 

Directly  below  the  phosphate  rock  horizon  occurs 
the  phosphatic  limestone  from  which  the  brown  rock 
itself  has  been  derived.  This  is  often  platy  in  structure, 
the  plates  of  highly  phosphatic  material  alternating 
with  the  nearly  pure  calcareous  layers.  This  platy  or 
laminated  structure  is  original  and  throws  light  on  the 
occurrences  of  the  brown  rock  itself  which  also  occurs 
in  plates  separated  by  layers  of  muck,  clay,  and  sand, 
the  former  corresponding  to  original  layers  of  phos- 
phatic limestone,  and  the  latter  to  the  intermediate  clay 
and  less  phosphatic  limestone  layers.  There  must  be  an 
enormous  tonnage  of  this  phosphatic  limestone  scattered 
throughout  the  phosphatic  rock  area  of  the  blue  grass 
region  of  Kentucky.  A  long  period  of  time  must  elapse 
before  any  attention  will  be  given  to  this  comparatively 
low  grade  material  as  a  source  of  phosphate,  but  it 
would  be  hazardous  to  say  that  this  will  never  be  done. 
Analyses  of  these  limestones,  some  of  which  are  in  a 
leached  and  some  in  a  partially  leached  condition,  oc- 
curring in  horses  between  cutters  contained  as  much  as 
70  per  cent,  calcium  phosphate,  and  Foerste  reports 
unaltered  phosphatic  limestone  in  the  Woodburn  mem- 
ber at  Versailles  containing  55.5  per  cent,  calcium  phos- 
phate.* In  Tennessee  some  of  this  phosphatic  limestone 
whose  analyses  the  writer  is  acquainted  with  averages 
more  than  42  per  cent,  in  calcium  phosphate.  The  car- 
bonate and  the  phosphate  of  calcium  mixture  in  this 
material  has  considerable  value  as  a  fertilizer  when  ap- 

*Kv.    Geol.    Survey,    Series   IV.,    Vol.    I,    Part   I,    1913,    p.   386. 

66 


plied  directly  to  the  land  in  finely  pulverized  form,  and 
although  it  is  difficult  to  predict  how  or  when  such  ma- 
terial will  be  utilized,  it  seems  fairly  certain  that  it  will 
prove  of  value  at  some  future  time. 

THE  FUTURE  OF  LOW  OR  INTERMEDIATE  GRADE 
PHOSPHATE  ROCK. 

GENERAL  REMARKS. 

There  is  associated  with  all  phosphate  rock  deposits 
considerable  rock  which  is  not  up  to  present  commercial 
requirements  in  content  of  calcium  phosphate.  There  is 
also  being  produced  in  connection  with  the  prepara- 
tion of  commercial  phosphate  rock  for  market  a  great 
deal  of  low  grade  material.  To  bring  these  classes  of 
material  up  to  commercial  grade,  that  is  to  a  grade  con- 
taining 70  per  cent,  or  more  calcium  phosphate,  various 
chemical  methods  have  been  used.  The  time  will  un- 
doubtedly come  when  these  chemical  methods  will  find 
much  more  extended  application  than  at  present,  and 
when  this  time  arrives  it  will  result  in  the  utilization  of 
a  great  deal  of  phosphate  rock  now  consigned  to  waste 
ponds  and  dumps,  and  also  much  which  will  not  bear  the 
present  cost  of  mining.  Such  methods  are  of  more  than 
ordinary  interest  in  connection  with  the  Kentucky  field. 
The  large  quantities  of  by-product  sulphuric  acid  which 
will  become  available  in  increasing  quantity  as  time  goes 
on  as  the  result  of  the  elimination  of  the  smelter  smoke 
nuisance,  is  an  important  element  in  the  situation.  Im- 
mense quantities  of  such  acid  has  in  the  past  been  avail- 
able in  southeastern  Tennessee,  and  is  potentially  avail- 
able at  the  smelters  in  the  vicinity  of  our  western  phos- 
phate field.  Indeed  the  chemical  method  of  concentrating 
phosphate  and  thus  enabling  it  to  be  transported  long 
distances  may  well  be  worked  out  in  connection  with  the 
high  grade  rock  that  the  western  phosphate  field  is  able 
to  produce,  and  it  will  also  be  the  means  of  conserving 
the  enormous  quantity  of  low  grade  phosphate  rock  in 
the  Kentucky  and  other  eastern  fields. 


67 


CHEMISTRY  OF  PROCESS. 

Phosphate  rock  is  marketed  now  as  such,  and  in 
the  form  of  acid  phosphate,  including  in  the  latter  term 
ordinary  super  and  donble-acid  phosphate,  the  latter  con- 
taining two  to  three  times  as  much  soluble  phosphoric 
acid  as  ordinary  super-phosphate. 

Before  the  discovery  of  the  extensive  high  grade 
deposits  of  phosphate  rock  in  this  country  aiul  abroad, 
the  manufacture  of  the  concentrated  grades  of  soluble 
phosphate  was  in  fairly  common  practice.  The  large 
supplies  of  high  grade  phosphate  rock  have  rendered  this 
unnecessary,  though  in  Europe  and  in  parts  of  the 
United  States  this  practice  is  reported  to  be  still  in  use. 

The  basic  reaction  involved  in  the  preparation  of 
soluble  acid  phosphate  takes  place  when  ordinary  rock 
phosphate  Oa,(P()4),  is  treated  with  sulphuric  acid. 
In  simple  form,  the  reaction  that  takes  place  may  be 
represented  thus : 

(1)  Ca,(P04),+3H,$04=2H,P04+3CaS04. 

(2)  4H:5P04+Ca,(P04)^3CaH4(P04)2. 
Eeduced  to  one  equation,  this  is  as  follows : 
Ca3(P04)2+2H2S04=CaH4(P04)2+2CaS04. 

In  the  presence  of  water,  which  has  been  omitted 
from  the  above  equations  in  order  to  simplify  them,  the 
calcium  sulphate  would  be  changed  into  gypsum  by  ab- 
stracting water  from  the  mass.  The  last  reaction  is  the 
one  desired  by  the  manufacturers. 

To  utilize  low  grade  rock  and  tailings,  and  to  make 
concentrated  phosphatic  fertilizers,  the  phosphoric  acid 
produced  by  the  first  reaction  is  evaporated  in  pans  until 
it  contains  about  45  per  cent,  phosphoric  anhydride.  It 
is  then  treated  with  a  fresh  supply  of  phosphate  rock, 
when  the  following  reaction  ensues: 

Ca3(P04)2+4H,PO4=3CaH4(P04)2. 

It  will  be  observed,  therefore,  that  ordinary  super- 
phosphate is  largely  a  mixture  of  soluble  calcium  phos- 
phate and  gypsum,  while  the  double  acid  phosphate  con- 
tains little  or  no  calcium  sulphate,  or  dehydrater,  and 
thus  has  to  be  artificially  dried.  Either  the  phosphoric 
acid  itself,  the  double  phosphate,  or  such  compounds  as 
potassium  or  ammonium  phosphate,  might  be  shipped 
from  our  western  field,  since  they  are  highly  concen- 
trated products. 

68 


EXPERIMENTAL  WORK  IN  THE  WEST. 
CHEMICAL  METHODS. 

With  reference  to  the  results  accomplished  to  date 
in  the  west  toward  the  production  of  a  high  grade  phos- 
phate product  which  may  be  shipped  to  eastern  markets, 
the  following  is  of  interest:* 

The  first  effort,  having  in  view  the  production  of 
a  high  grade  phosphate  product  which  would  stand  the 
cost  of  shipment  to  eastern  markets,  was  instituted  by 
the  Mountain  Copper  Company,  at  Martinez,  California. 
This  company  for  many  years  has  been  producing  and 
marketing  locally  a  super-phosphate,  and  some  years 
ago  endeavored  to  produce  a  high  grade  product.  The 
possibility  of  making  a  high  grade  phosphate  product 
has  also  been  considered  and  discussed  by  the  technical 
staff  of  the  American  Smelting  and  Refining  Company 
in  connection  with  their  acid  plant  at  Garfield,  Utah. 

At  Anaconda  during  the  past  two  years  a  consistent 
and  elaborate  investigation  with  a  high  grade  phosphate 
product  in  view  has  been  made.  The  desire  has  been  to 
obtain  an  outlet  for  the  waste  sulphur  dioxide  gas  of  the 
smelter  through  the  production  and  utilization  of  sul- 
phuric acid.  The  investigation  was  started  on  a  small 
scale  in  the  laboratory,  and  is  now  advanced  to  the  point 
where  a  unit  of  500  pounds  of  phosphate  rock  per  day 
capacity  is  being  operated.  Stated  briefly,  the  results 
obtained  up  to  the  present  time  are  as  follows : 

Decomposition  of  the  phosphate  rock  containing 
from  30  to  33  per  cent.  P205  has  been  effected  by  grind- 
ing with  dilute  sulphuric  acid,  agitation  with  acid,  or 
treatment  with  acid  in  a  "den,"  as  in  the  manufacture 
of  ordinary  super-phosphate.  The  best  recoveries  have 
been  made  by  using  the  "den"  decomposition  followed 
by  leaching. 

The  rock  is  first  treated  with  nearly  the  theoretical 
amount  of  sulphuric  acid  in  a  "den"  to  take  care  of  the 
lime.  The  mixture  ' '  sets ' '  after  a  few  minutes  stirring 
and  usually  is  allowed  to  stand  covered  for  16  hours  at 
about  40°  C.  The  mixture  is  then  leached  with  solutions 
from  previous  teachings  containing  about  6  per  cent, 
sulphuric  acid.  The  material  filters  quite  satisfactorily 

^Communicated    by    A.    E.    Wells    of   the    Mine    Experiment    Station    of 
the  Bureau  of  Mines   at   Salt   Lake  City,    Utah. 

69 


when  the  sulphuric  acid  content  of  the  leaching  solution 
is  properly  maintained,  and  the  resulting1  solution  may 
contain  as  high  as  20  per  cent.  PL,O-.  The  extraction  is 
about  90  per  cent  of  the  P203  in  the  rock. 

In  one  line  of  investigation  the  solutions  were  evap- 
orated to  about  45  per  cent.  P20.-,,  at  which  concentration 
some  calcium  sulphate  was  deposited.  This  phosphoric 
acid  solution  was  then  added  to  more  phosphate  rock, 
the  amount  of  rock  used  being  about  80  per  cent,  of  that 
theoretically  required  to  combine  with  the  phosphoric 
acid,  according  to  the  reaction:  Ca:,(PO4)2+4HoPOi— 
3CaH4(P04)o.  The  mixtiue  \vas  alio\v<  d  t;>  stand  for  sev- 
eral hours  and  then  dried.  A.  <h.  v  ,grindable  product  con- 
taining about  50  per  cent,  available  I'M)-  was  obtained. 

Another  line  of  investigation  has  aimed  to  produce 
a  high  grade  phosphoric  acid  liquor  or  even  glacial  phos- 
phoric acid.  The  solutions  from  the  leaching  mentioned 
above  have  been  evaporated  on  steam  baths  to  the  point 
where  they  contain  (J2  per  cent.  P^O-.  As  stated  above, 
calcium  sulphate  begins  to  deposit  when  the  concentra- 
tion reaches  about  40  per  cent.  P20r>,  and  continues  to 
deposit  as  the  concentration  increases.  In  the  laboratory 
all  evaporations  were  effected  in  lead  or  glass,  as  the 
dilute  solutions  corroded  iron  rapidly.  In  some  long-time 
evaporations,  a  glacial  acid,  a  mixture  of  pyro  and  meta 
phosphoric  acM  resulted,  containing  as  much  as  70  to 
80  per  cent.  P20n. 

Experiments  are  in  progress  in  connection  with  the 
work  now  being  conducted  on  the  500-pound  unit,  to  detor- 
mino  the  possibility  of  evaporation  in  a  tower  such  as  is 
used  in  sulphuric  acid  concentration.  At  the  Bureau  of 
Mines  experiment  station  in  Salt  Lake  City,  tests  are 
in  progress  to  determine  whether  the  solution  can  be 
evaporated  to  a  dry  P?0r>  powder  by  spraying  the  dilute 
or  partially  evaporated  solutions  into  a  stream  of  hot 
gases  and  precipitating  the  dehydrated  acid  by  electrical 
profvrvta+ion  methods.  The  evaporation  problem  still 
remains  the  most  serious  one  in  the  production  of  a  high 
grade  phosphoric  acid  liquor  or  of  glacial  phosphoric 
ac?d.  Due  to  the  hvgrosconic  pror>erties  of  the  glacial 
acid,  and  the  necessitv  of  shipping  it  in  sealed,  iron  con- 
tainers, it  is  believed  that  it  will  be  most  feasible  to 


70 


prepare  a  60  to  65  per  cent.  P205  solution  to  be  shipped 
in  tank  cars. 

The  possibility  of  substituting  this  phosphoric  acid 
solution  for  sulphuric  acid  in  the  recovery  of  ammonia  at 
the  by-product  coke  plants  with  the  production  of  am- 
monium phosphate,  is  being  investigated.  No  data  from 
this  investigation  are  yet  available. 

Though  it  is  true  that  the  grade  of  rock  on  which 
work  has  been  done  contains  fairly  high  percentages  of 
phosphoric  acid,  theie  is  in  MOM  tana,  witliin  a  distance 
of  30  miles  of  the  Anaconda  smelter,  large  deposits  of 
phosphate  rock  which  will  average  only  about  23  per 
cent,  P20r,,  and  in  time  it  is  likely  that  these  deposits 
will  be  of  considerable  value.  At  the  present  time  the 
phosphoric  acid  solutions  from  this  grade  of  rock  con- 
tain so  much  iron  and  alumina  that  it  has  been  felt  that 
it  would  be  much  better  to  work  out  the  problem  with 
the  use  of  the  higher  grade  rock,  of  which  a  great  deal  is 
present  and  can  be  easily  mined  in  southern  Idaho  and 
northern  Utah. 

ELECTRICAL  METHODS. 

An  interesting  and  recent  development  in  the  utili- 
zation of  low  grade  phosphate  rock  is  in  the  production 
of  phosphoric  acid  and  its  derivatives,  ammonium  phos- 
phate and  double  super-phosphate,  by  utilization  of  the 
electric  furnace.  Sulphuric  acid  is  here  replaced  by 
silica,  coke,  and  electric  energy,  and  with  very  cheap 
electric  energy,  the  resulting  product  may  be  produced 
considerably  cheaper  and  in  a  much  more  available  form 
than  by  the  present  methods.  The  fertilizers-  produced 
with  the  aid  of  electric  energy,  fixed  nitrogen  and  avail- 
able phosphoric  acid,  go  hand  in  hand  with  cheap  water 
power. 

Ross,  Carothers,  and  Merz*  have  recently  summar- 
ized the  results  of  certain  experiments  in  the  use  of  the 
Cottrell  precipitator  in  recovering  phosphoric  acid  evolv- 
ed in  the  volatilization  method  of  treating  phosphate 
rock  by  ignition  with  coke  and  silica  in  an  electric 
furnace.  "A  current  of  air  which  was  passed  over  the 

*Ross,  W.  H.,  Carothers,  J.  N.,  Mf-r?,  A.  R.  T'-p  use  of  the  Cottrell 
precipitator  in  recovering-  the  phosphoric  acid  evolved  in  the  volatiliza- 
tion method  of  treating"  phosnhate  rock.  Journal  of  Industrial  and 
Engineering-  Chemistry,  Vol.  IX.,  No.  1,  January  1,  1917,  pp.  26-31. 

71 


charge  in  the  furnace  served  the  double  purpose  of 
oxidizing  the  fumes  of  phosphorus  to  phosphorus  pentox- 
ide  and  of  carrying  the  latter  to  the  precipitator.  In  one 
series  of  experiments  the  fumes  from  the  furnace  before 
entering-  the  precipitator  were  passed  through  a  tower 
provided  Avith  baffle  plates  which  had  the  effect  of  cool- 
ing- down  the  gases  to  about  ordinary  temperature.  Tn 
a  second  series  of  experiments  the  tower  was  cut  out  and 
the  fumes  passed  almost  directly  into  the  precipitator 
at  a  temperature  above  100°  C.  In  each  case  the  phos- 
phorus pentoxide,  which  takes  up  water  from  the  current 
of  air  passing  through  the  furnace  and  also  from  the 
moisture  driven  off  from  the  charge,  is  precipitated  in 
the  form  of  a  solution  of  phosphoric  acid.  When  the 
precipitation  is  made  at  temperatures  about  100°,  or 
above,  the  concentration  of  the  acid  is  greater  than  that 
collected  at  a  lower  temperature,  but  by  reducing  the  flow 
of  air  through  the  furnace,  acid  of  high  concentration 
may  also  be  obtained  with  low  temperature  precipita- 
tion. 

44  The  advanutages  of  this  method  of  collecting  the 
phosphoric  acid  over  the  scrubbing  tower  method  now 
in  use4  are  as  follows: 

"1.  The  equipment  required  is  simple  in  construc- 
tion and  automatic  in  operation. 

"2.  The  simplicity  of  the  construction  of  the  pre- 
cipitating pipes  decreases  the  difficulties  arising  from  the 
corrosive  action  of  the  phosphoric  and  hydrofluoric  acids 
evolved  from  the  phosphate  rock. 

"3.  In  this  way  there  may  be  recovered  phosphoric 
acid  of  a  high  degree  of  purity  suited  for  direct  use  with- 
out further  purification  in  those  industries  where  a  rela- 
tively pure  acid  is  required. 

"4.  A  more  concentrated  acid  can  be  obtained  in 
this  way  than  is  possible  to  prepare  directly  by  any 
other  commercial  process,  and  when  this  acid  is  used  in 
the  preparation  of  concentrated  fertilizers,  such  as 
mono-ammonium  phosphate,  a  dry  product  may  be  ob- 
tained directly  without  the  necessity  of  evaporating  so- 
lutions, or  of  drying  the  resultant  product. 

"This  is  the  first  time  that  the  Cottrell  precipitator 
has  been  used  for  the  precipitation  of  a  product  which 

72 


has  been  purposely  volatilized  with  a  view  to  its  recovery 
in  this  way." 

The  fertilizer  division  of  the  Bureau  of  Soils  has 
given  considerable  attention  to  the  preparation  of  con- 
centrated fertilizers  and  a  paper  recently  prepared  by 
William  H.  Ross  and  Albert  R.  Merz*  gives  a  general  ac- 
count of  some  methods  which  may  prove  to  be  applicable 
in  their  preparation.  The  one  which  concerns  this  paper 
more  especially  relates  to  the  preparation  of  phosphoric 
acid  together  with  potassium  and  ammonium  phosphates. 

Practically  the  entire  output  of  fertilizers  in  the 
United  States  is  consumed  east  of  the  Mississippi  river, 
and  more  than  four-fifths  of  this  consumption  is  in  the 
states  bordering  on  the  Atlantic  Ocean  and  the  Gulf  of 
Mexico.  Our  natural  resources  in  phosphate  rock,  how- 
ever, occur  in  overwhelming  preponderance  in  the  far 
west.f 

"A  serious  problem  presents  itself  in  bringing  these 
raw  materials  or  products  derived  from  them  to  the 
region  of  consumption,  as  the  distances  are  great  and  the 
only  means  of  transportation  available,  that  by  rail,  is 
expensive.  A  partial  solution  of  this  problem  is  found 
in  the  production  of  concentrated  fertilizers,  whereby 
the  ratio  of  the  cost  of  transportation  to  the  value  of  the 
material  shipped  is  considerably  diminished. 

"The  simplest  of  these  commercial  fertilizers  in 
chemical  constitution  is  phosphoric  acid.  The  processes 
which  have  been  used  commercially  for  the  preparation 
of  this  acid  may  be  conveniently  divided  into  two  classes, 
as  follows:  (1)  Processes  which  involve  treatment  of 
the  rock  with  a  mineral  acid  such  as  sulphuric  acid ;  and 
(2)  processes  in  which  the  phosphorus  is  evolved  from 
the  rock  by  ignition  with  silica  and  coke  and  its  subse- 
quent conversion  into  phosphoric  acid  through  oxidation 
and  absorption  of  the  anhydride  in  some  form  of  scrub- 
bing tower.  With  the  volatilization  method  it  has  been 
found  possible  to  prepare  an  acid  of  greater  concentra- 
tion than  it  is  possible  to  obtain  directly  in  any  process 
of  the  first  group,  but  even  in  this  process  when  the 

*Ross,  W.  H.,  and  Merz,  A.  R.  The  preparation  of  concentrated 
fertilizers:  The  American  Fertilizer.  Vol.  45,  No.  8,  October  14,  1916,  pp. 
32-35. 

fSee  paper  by  Phalen,  W.  C.  The  conservation  of  phosphate  rock  in 
the  United  States:  Trans.  Am.  Inst.  Min.  Engrs.,  Bull.  119,  November, 
1916,  pp.  1901-1934. 

73 


scrubbing  tower  method  of  recovering  the  phosphoric 
acid  is  used  it  is  impractical  to  obtain  an  acid  of  greater 
strength  than  about  50  per  cent,  phosphorus  pentoxide 
and  evaporation  must  be  resorted  to  for  further  concen- 
tration. However,  if  the  scrubbing  tower  be  replaced  by 
a  Cottrell  prccipitator,  no  difficulty  is  found  in  securing 
phosphoric  acid  which  contains  upward  of  95.0  per  cent, 
phosphoric  acid.  A  high  grade  phosphate  rock  of  75 
per  cent  tricalciuin  phosphate  has  34.4  per  cent.  P^, 
whereas  a  95.0  per  cent,  phosphoric  acid  solution  con- 
tains 68.8  per  cent  P205.  Therefore  we  have  produced  a 
fertilizer  material  twice  as  concentrated  as  high  grade 
rock  or  over  four  times  as  concentrated  as  16  per  cent, 
super-phosphate  and  having  all  the  P^O-,  in  the  so-called 
available  form.  It  may  be  interesting  to  note  that  this 
is  the  first  time  that  the  Cottrell  precipitator  has  been 
used  for  llie  precipitation  of  a  product  which  has  been 
purposely  volatilized  with  a  view  to  its  recovery  in  this 
way.  A  detailed  description  of  the  experiments  con- 
ducted with  the  precipitator  and  the  advantages  of  its 
application  are  given  in  the  paper  referred  to  above. 

"The  phosphoric  acid  which  is  produced  by  this 
procedure  may  be  shipped  directly  in  suitable  containers 
to  the  region  of  fertilizer  consumption,  there  to  be  used 
in  the  preparation  of  mixed  fertilizers.  This  is  now 
actually  being  considered  by  a  western  concern  which 
contemplates  shipping  phosphoric  acid  that  has  been  ex- 
tracted from  western  phosphates  by  the  sulphuric  acid 
method  and  concentrated  by  evaporation." 

The  studies  made  by  Ross  and  Mcrz  also  include  the 
direct  preparation  of  salts  in  which  the  phosphoric  acid 
was  combined  with  a  fertilizer  base  such  as  potassium 
and  ammonium  to  produce  the  corresponding  potassium 
(KoP04)  and  ammonium  phosphate  ((NH4)3P04). 
Methods  of  producing  a  concentrated  fertilizer  contain- 
ing all  three  fertilizer  elements,  that  is  nitrogen,  potash, 
and  phosphorus,  are  also  outlined. 

THE  FUTURE  OUTLOOK  FOP,  THE  KENTUCKY 
PHOSPHATE  FIELD. 

From  what  has  been  stated  with  reference  to  the 
Kentucky  phosphate  field,  it  is  evident  that  rock  of  high 
grade  has  been  found  in  different  places  in  the  blue  grass 

74 


region  of  central  Kentucky,  and  without  doubt  many 
more  workable  deposits  will  be  found  as  the  entire  region 
is  systematically  and  carefully  prospected  according  to 
the  methods  usually  employed  in  this  work  and  outlined 
in  this  paper. 

A  somewhat  restricted  district  in  the  vicinity  of 
Wallace,  a  few  miles  south,  southeast  and  southwest  of 
Midway,  Woodford  County,  is  the  only  one  of  prom- 
inence within  which  phosphate  rock  is  found  to  occur  to 
any  great  extent.  Between  Midway  and  Spring  Station, 
along  the  Louisville  and  Nashville  Railroad,  and  on  cer- 
tain farms  to  the  north  of  the  railroad,  is  another  area 
where  phosphate  rock  has  been  found  in  some  quantity. 
The  limits  of  these  areas  have  not  been  very  accurately 
determined,  but  enough  drilling  has  been  done  to  indicate 
that  very  important  deposits  of  phosphate  rock  should 
be  expected  to  be  found  locally.  When  it  is  remembered 
that  brown  rock  phosphate  may  run  from  600  to  1,000 
tons  per  acre  per  foot  of  thickness,  small  areas  may 
prove  of  great  importance  if  the  phosphate  deposits  in 
them  are  thick  enough  and  of  good  quality. 

Outside  of  the  Wallace  area  and  that  to  the  west  of 
Midway,  phosphate  rock  is  known  to  occur  in  and  around 
Lexington,  Fayette  County,  in  the  vicinity  of  George- 
town, Scott  County,  near  the  Forks  of  Elkhorn,  Franklin 
county,  near  Versailles,  Woodford  County,  and  near  Pine 
Grove  Station,  Clark  County. 

The  material  collected  from  the  drillings  made  in 
this  field  shows  great  variation  in  content  of  calcium 
phosphate,  and  the  sections  themselves  also  show  great 
irregularity  in  the  thickness  of  the  phosphate  bed.  In  the 
Wallace  district,  of  the  total  number  of  analyses  made 
of  materials  collected  from  drillings,  about  one-third 
showed  a  content  of  50  per  cent,  or  more  of  calcium  phos- 
phate. Less  than  10  per  cent,  of  the  total  showed  a  con- 
tent between  60  and  70  per  cent.,  and  but  5  per  cent,  of 
the  total  showed  more  than  70  per  cent.  The  latter  ma- 
terial was,  for  the  most  part,  collected  from  well  exposed 
sections  in  the  old  workings  of  the  Central  Kentucky 
Phosphate  Company,  near  Wallace.  The  remaining:  65 
ppr  cent,  contained  less  than  50  per  cent,  calcium  phos- 
phate, and  the  great  bulk  of  the  material  carried  from 
30  to  50  per  cent.  The  other  localities  in  which  prospect- 

75 


ing"  was   carried  on  showed  approximately   similar   re- 
sults. 

Occasional  occurrences  of  lump  rock  were  found  in 
this  area,  containing  more  than  80  per  cent,  calcium 
phosphate,  and  although  rock  in  workable  quantity  may 
be  found  running  up  to  and  above  present  commercial 
requirements,  that  is,  containing  70  per  cent,  and  more 
calcium  phosphate,  it  is  quite  safe  to  affirm  that  the  bulk 
of  Kentucky  rock  will  be  found  to  contain  less  than  70 
per  cent.  BPL.  This  means  that  in  the  most  promising 
areas  the  rock  will  have  to  be  carefully  washed  and 
cheaply  worked  by  the  most  modern,  labor  saving  de- 
vices, to  bring  it  up  to  present  commercial  standards 
so  that  it  will  be  able  to  compete  in  the  open  market  with 
Tennessee  rock.  Without  doubt,  much  of  the  Kentucky 
rock  of  low  or  intermediate  grade  must  wait  for  cheap 
chemical  or  electrical  processes  of  concentration.  Some 
of  the  very  latest  developments  in  these  processes  are 
described^  in  this  paper. 

The  Kentucky  phosphate  field  is  practically  a  virgin 
field.  From  its  study  and  a  comparison  of  it  with  the 
Tennessee  field,  it  is  felt  that  local  conditions  are  sim- 
ilar and  the  problem  of  working  the  Kentucky  phosphate 
deposits  must  be  along  much  the  same  lines  as  in  Ten- 
nessee. For  this  reason,  brief  descriptions  of  the  tech- 
nology of  the  mining  and  preparation  of  phosphate  rock 
for  market  as  practiced  in  the  Mt.  Pleasant  district  of 
Tennessee  are  given. 

The  advantages  of  the  Kentucky  field  with  respect 
to  transportation  rates  to  markets  in  the  north  and  west 
are  pointed  out.  Though  the  Kentucky  field  has  an  ad- 
vantage in  freight  rates  to  important  fertilizer  markets 
in  Ohio,  Indiana  and  Illinois,  this  has  not  led  to  the  es- 
tablishment of  any  important  industry  in  the  State  thus 
far.  The  Tennessee  field,  the  pioneer,  has  enjoyed  the 
advantages  usually  accruing  to  the  first  in  the  field.  The 
Tennessee  rock,  on  the  average,  is  a  higher  grade  rock 
than  the  Kentucky,  which  gives  the  former  certain  ad- 
vantages, until  effective  concentration  methods,  either 
mechanical,  chemical,  or  both,  are  introduced  in  the  Ken- 
tucky field. 

The  lands  on  which  the  Kentucky  rock  phosphate 
has  been  found  are  very  fertile,  in  fact  are  the  most 

76 


fertile  in  the  blue  grass  region.  Consequently  they 
possess  high  values  for  farm  and  grazing  purposes,  and 
are  worth  at  least  $200  per  acre  for  these  purposes  alone. 
The  extent  to  which  the  Kentucky  field  will  be  developed 
depends  not  only  on  what  may  underlie  the  land,  but  on 
the  attitude  assumed  by  the  farmers  who  own  it.  Whether 
it  is  considered  more  valuable  for  farming  purposes  than 
for  the  phosphate  deposits  which  underlie  it  in  places,  re- 
mains to  be  seen,  assuming,  of  course,  that  exact  knowl- 
edge with  regard  to  its  mineral  wealth  becomes  better 
known  as  time  goes  on.  It  is  certain  that  after  mining 
operations  have  been  conducted  it  will  cost  much  to 
bring  the  land  into  condition  for  farming,  if  this  can  be 
done  at  all.  In  this  connection,  however,  it  is  of  interest 
to  point  out  that  in  Tennessee,  whore  hydraulic  mining 
is  practiced  in  one  locality,  the  rock  is  mined  out  in  a 
small  area  and  the  overburden  from  that  next  to  it  is 
washed  into  the  area  which  has  been  mined  out.  The 
resultant  topography  is  level  and  may  be  farmed  over 
again,  a  most  important  consideration  where  the  land  is 
as  valuable  as  in  the  Kentucky  Blue  Grass  region.  Ac- 
cording to  this  method  of  removing  overburden,  the  land 
is  conserved  for  farming  purposes  for  future  genera- 
tions and  greatly  improved  at  the  same  time,  for  a  part 
of  the  phosphate  rock  and  sand  formerly  below  the  sub- 
soil is  thoroughly  incorporated  into  the  top  soil,  and  the 
fertilizer  value  of  the  phosphate  rock  thus  rendered 
available  in  time. 

Many  extensive  deposits  of  low  grade  Kentucky 
rock  may  be  expected  to  become  profitable  in  the  future, 
as  methods  for  their  practical  utilization  are  solved,  and 
as  the  supply  of  high  grade  rock  in  other  eastern  states 
shall  have  become  exhausted. 


BIBLIOGRAPHY   OF    PUBLICATIONS    RELATING    TO    PHOSPHATE 

ROCK. 

BAKU.  JAMES  A.,  Tennessee  phosphate  practice:  Trans.  Am.  Inst.  Min. 
Engrs.,  Bull.  93,  Sept.,  1914,  pp.  2397-2413. 

-  The  use  of  low  grade  phosphate:   Trans.  Am.  Inst.  Min.  Engrs., 
Bull.   110,  Feb.,  1916,  pp.   243-245. 

Bi.AcivWKi.DEK,  ELIOT,  Phosphate  deposits  east  of  Ogden,  Utah:  U.  S. 
Geol.  Survey,  Bull.  430,  pp.  536-551,  1910. 

-  A  reconnaissance  of  the  phosphate  deposits  in  western  Wyom- 
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C n ATARI).  T.  M.,  Phosphate  chemistry  as  it  concerns  the  miner:  Trans. 
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DARTOX.  N.  H.,  and  SIEKEXTIIAL.  C.  E.,  Geology  and  mineral  resources 
of  the  Laramie  Basin,  Wyo.;  a  preliminary  report:  U.  S.  Geol. 
Survey  Bull.  364,  pp.  81,  1909. 

ECKEL,  E.  C.,  Recently  discovered  extension  of  Tennessee  white-phos- 
phate field:  U.  S.  Geol.  Survey  Mineral  Resources,  1900  pp.  812-813, 
1901. 

-  Utilization  of  iron  and  steel  slags:    U.  S.  Geol.  Survey  Bull.  213, 
pp.   221-231,   1903. 

-  The  white  phosphates  of  Decatur  County,  Tenn.:    U.   S.   Geol. 
Survey  Bull.  213,  pp.  424-425,  1903. 

Ei.iminGK.  G.  H.,  A  preliminary  sketch  of  the  phosphates  of  Florida:  Am. 

Inst.  Min.  Eng.  Trans.,  Vol.  21,  pp.  196-231,  1893. 

FOKHSTK.  A.  E.,  The  phosphate  deposits  in  the  upper  Trenton  lime- 
stones of  Central  Kentucky:  Ky.  Geol.  Survey,  Series  IV.,  Vol.  I., 

Part  I.,  1913,  pp.  391-439. 
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Bull.  470,  pp.  440-451,  1911. 
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deposits   in   southeastern    Idaho   and   adjacent   parts   of  Wyoming 

and  Utah:    U.  S.  Geol.  Survey  Bull.  430,  pp.  457-535,  1910. 
GARDNER.  JAMES  H.,  Rock  phosphate  in  Kentucky:   Mines  and  Minerals, 

November,   1912,   pp.   207-209. 
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of  Idaho,  Utah,  and  Wyoming:  U.  S.  Geol.  Survey  Bull.  436,  82  pp., 

1910. 
HAYES,  C.  W.,  The  Tennessee  phosphates:  U.  S.  Geol.  Survey,  Sixteenth 

Ann.  Rept.,  pt.  4,  pp.  610-630,  1895;   Seventeenth  Ann.  Rept.,  pt.  2, 

pp.  519-550,  1896. 

—  The  white  phosphates  of  Tennessee:  Am.  Inst.  Min.  Eng.  Trans., 

Vol.  25,  pp.  19-28,  1896. 

78 


-  A  brief  reconnaissance  of  the  Tennessee  phosphate  field:   U.  S. 
Geol.   Survey,  Twentieth  Ann.  Kept.,  pt.  6,  continued,  pp.  633-638, 
1899. 

-  The  geological  relations  of  the  Tennessee  brown  phosphates: 
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Ann.    Kept.,   pt.    3,   pp.    473-485,   1901. 

-  Origin   and   extent  of  the   Tennessee   white   phosphates:    U.    S. 
Geol.    Survey   Bull.    213,   pp.    418-423,    1903. 

HOOK,  J.  S.,  The  brown  and  blue  phosphate  rock  deposits  of  South  Cen- 
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1914,  pp.  51-83. 

-  The  white  phosphates  of  Tennessee:    The  Resources  of  Tennes- 
see, Vol.   V.,  No.   1,  January,   1915,  pp.   23-33. 

IHLSENG,  M.  C.,  A  phosphate  prospect  in  Pennsylvania:  U.  S.  Geol.  Sur- 
vey, Seventeenth  Ann.  Rept.,  pt.  3,  continued,  pp.  955-957,  1896. 

MATSOX,  G.  C.,  The  phosphate  deposits  of  Florida:  U.  S.  Geol.  Survey 
Bull.  604,  pp.  101,  17  pis.,  1915. 

MANSFIELD,  G.  R.,  A  reconnaissance  for  phosphate  in  the  Salt  River 
Range,  Wyo.:  U.  S.  Geol.  Survey  Bull.  620,  pp.  331-349,  1915. 

MAYNAKD,  T.  POOLK,  White  rock  phosphates  of  Decatur  County,  Tennes- 
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161-169. 

MEMMINGEU,  C.  G.,  Commercial  development  of  the  Tennessee  ph6s- 
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79 


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80 


Plate  I. 

View  of  Brannon  cherty  limestone  with  upper  contorted  limestone 
layer  and  overlying  phosphate  rock  debris.  Cut  on  Queen  &  Crescent 
Route  near  Virginia  Avenue  bridge,  Lexington,  Ky. 


Plate  II. 

View    showing   irregular    bedding    in    the    Brannon    cherty    limestone 
near  Virginia  Avenue  bridge,  Lexington,  Ky. 


Plate  III. 

Crushed  zone  in  limestone  in  the  Brannon  member.  East  side  of 
Versailles-Frankfort  pike,  about  3  miles  north  of  Versailles,  Woodford 
County,  Ky. 


Plate  IV. 

Old  McMeekin  limestone  quarry,  Newtown  pike,  3  miles  north  of 
Lexington,  Ky.  In  this  quarry  Dr.  R.  Peter  first  noted  the  association 
of  cyclora  and  phosphate  rock. 


Plate  V. 

Arching  of  phosphate  rock  over  limestone  horse.  Note  the  band- 
ing in  the  phosphate  rock  and  also  in  the  limestone.  United  Phosphate 
and  Chemical  Co.,  near  Wallace,  Ky. 


Plate  VI. 

Arching  of  phosphate   rock    beds   over  underlying  limestone. 
United  Phosphate  and  Chemical  Company,  near  Wallace,  Ky. 


Plate  VII. 

Limestone  with  interlaminated  phosphatic  layers.  Type  of  rock 
from  which  phosphate  deposits  are  derived.  Quarry  on  Haggin  estate, 
east,  of  Maysville  pike,  7  miles  northeast  of  Lexington,  Kentucky. 


Plate  VIII. 

Alternating  layers  of  limestone  and  phosphatic  material,  Mt.  Pleasant, 

Tenn. 


Plate  IX. 

View   in   old    phosphate    workings    showing    "cutters"    and    limestone 
"horses."     Near  Wallace,  Ky. 


Plate  X. 

Arching  of  phosphate  rock  over  limestone  horses.     Near 
Mt.  Pleasant,  Tenn. 


Plate  XI. 

Rafinesquina  alternata  from  near  Versailles,  Woodford  County,  Ky. 
The  shell  has  been  replaced  by  SiO2  and  Ca3  (PO4)2  has  infiltrated 
and  formed  a  cast  of  the  interior  of  the  shell. 


Plate  XII. 

Removing  overburden  with  scrapers.     Near  Scotts  Mill,  Maury  County, 

Tenn. 


Plate  XIII. 

Distant  view  of  a  cantilever,  showing  an  open  pit  in  part  worked 
out,  Mt.  Pleasant,  Tenn.  Note  the  method  of  disposing  of  overburden; 
limestone  horses,  cutters,  and  phosphate  rock  curving  over  horses. 


Plate  XIV. 

A  typical  drag  line  excavator  at  work  stripping  overburden. 
Mt.   Pleasant,   Tenn. 


Plate  XV. 
A  steam  shovel  removing  overburden,  Mt.  Pleasant,  Tenn. 


Plate  XVI. 

Mining  phosphate  rock  with  hydraulic  gun,  near  Mt.  Pleasant,  Term. 
Overburden  is  also  removed  by  this  method. 


Plate  XVII. 

Drying  phosphate  rock  by  burning  in  open  kilns,  Mt.  Plea-sant,  Tenn. 


Plate  XVIII. 

A  deep  and  wide  cutter.     Shows  the  method  of  removing  phosphate 
rock  by  hand  from  deep  cutters.    Mt.  Pleasant,  Tenn. 


Plate  XIX. 

A  very  narrow  cutter  from  which  it  is  difficult  to  remove  the  phosphate, 
rock,  Mt.  Pleasant,  Tenn. 


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